Stop playing with data: there is no sound evidence that Bacille Calmette-Guérin may avoid SARS-CoV-2 infection (for now)

Association between presence of Bacillus Calmette-Guerin vaccine scar and coronavirus disease 2019

Bacillus Calmette-Guerin vaccine is administered for protection against tuberculosis and may also have beneficial effects against some viral respiratory tract infections. In this study, it was aimed to investigate the relationship between Bacillus Calmette-Guerin vaccination which is confirmed by BCG scar, and the frequency and course of Coronavirus disease 2019 (COVID-19). Among 490 patients, 400 patients who accepted to participate in the study were included. After the consent of patients, age, gender, body mass index, comorbidities, smoking, history, and the progress of COVID-19 of these patients were investigated; the presence and number of Bacillus Calmette-Guerin scars were recorded by a physician. Data from groups with and without COVID-19 history were compared. There was no relation between presence and number of the BCG scar and COVID-19 related hospitalization and intensive care unit admission. When groups with and without COVID-19 history compared, no statistically significant difference was found with the presence and number of Bacillus Calmette-Guerin scars (P > 0,05). No association was found between the presence or number of BCG scars and the frequency and course of COVID-19 in individuals with Bacillus Calmette-Guerin vaccination history confirmed by the presence of Bacillus Calmette-Guerin vaccine scars. Currently, the most important protection against COVID-19 is the COVID-19 vaccine.

Effectiveness of Bacille Calmette-Guerin vaccination policies in reducing infection and mortality of COVID-19: a systematic review

BACKGROUND

COVID-19 vaccination has been advocated as the most effective way to curb the pandemic. But with its inequitable distribution and slow rollout, especially in low- to middle- income countries, it will still take a long time before herd immunity is achieved. Alternative measures must therefore be explored to bolster current COVID-19 vaccination efforts. In particular, the Bacille Calmette-Guerin vaccine has been studied extensively as to its proposed conferment of non-specific immunity against different infections, including COVID-19. The aim of this study, therefore, is to evaluate the current evidence on the effectiveness of national BCG vaccination policies in reducing infection and mortality of COVID-19.

METHODS

A systematic review was conducted between April to August 2021 following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA-P) guidelines. Literature was retrieved from PubMed, Cochrane, HERDIN, Web of Science, EBSCO, and Western Pacific Region Index Medicus (WPRIM). Studies conducted from January 2020 to August 2021 that fell within Level 1A to 2C of the Oxford Center for Evidence-Based Medicine were included in the review. Quality assessment was performed using the appropriate Joanna Briggs Institute critical appraisal tool and a quality assessment checklist for ecological studies adapted from Betran et al. RESULTS: A total of 13 studies were included in this review. Nine studies reported significant association between BCG vaccination policies and COVID-19 outcomes, even when controlling for confounding variables. In addition, among other mandated vaccines, such as pneumococcal, influenza, diphtheria-tetanus-pertussis, and measles, only BCG vaccination showed significant association with decreased COVID-19 adverse outcomes. However, other factors also showed positive association with COVID-19 outcomes, particularly markers of high economic status of countries, higher median age, and greater population densities.

CONCLUSION

The lower incidence and mortality of COVID-19 in countries with mandated BCG vaccination may not solely be attributable to BCG vaccination policies, but there is still some evidence that demonstrates a possible protective effect. Clinical trials must be continued before recommendations of BCG vaccinations are to be used as an alternative or booster vaccine against COVID-19.

COVID-19 and Beyond: Exploring Public Health Benefits from Non-Specific Effects of BCG Vaccination

Bacille Calmette–Guérin (BCG) vaccination, widely used throughout the world to protect against infant tuberculous meningitis and miliary tuberculosis (TB), can provide broad non-specific protection against infectious respiratory diseases in certain groups. Interest in BCG has seen a resurgence within the scientific community as the mechanisms for non-specific protection have begun to be elucidated. The impact of the COVID-19 pandemic on nearly every aspect of society has profoundly illustrated the pressure that respiratory infections can place on a national healthcare system, further renewing interest in BCG vaccination as a public health policy to reduce the burden of those illnesses. However, the United States does not recommend BCG vaccination due to its variable effectiveness against adult TB, the relatively low risk of Mycobacterium tuberculosis infection in most of the United States, and the vaccine’s interference with tuberculin skin test reactivity that complicates TB screening. In this review, we explore the broad immune training effects of BCG vaccination and literature on the effects of BCG vaccination on COVID-19 spread, disease severity, and mortality. We further discuss barriers to scheduled BCG vaccination in the United States and how those barriers could potentially be overcome.

Variances in BCG protection against COVID-19 mortality: A global assessment

The BCG vaccine is known to impart nonspecific immunological benefits alongside conferring protection to tuberculosis in endemic regions. It is also known to protect against bladder cancer and other respiratory tract infections. During the coronavirus disease 2019 (COVID-19) pandemic, the BCG vaccine has gained attention due to its role in conferring protective immunity. We demonstrate the potential immunological protective mechanisms that play a role against COVID-19. We conduct a global assessment of the countries that have the highest and lowest mortality rates determined by an a priori methodology. Lastly, we discuss the potential limitations of incorporating BCG vaccines as potential strategies against COVID-19 and provide recommendations regarding their use in ongoing and future epidemics.

Harnessing the non-specific immunogenic effects of available vaccines to combat COVID-19

No proven remedy is identified for COVID-19 yet. SARS-CoV-2, the viral agent, is recognized by some endosomal and cytosolic receptors following cell entry, entailing innate and adaptive immunity stimulation, notably through interferon induction. Impairment in immunity activation in some patients, mostly elderlies, leads to high mortalities; thus, promoting immune responses may help. BCG vaccine is under investigation to prevent COVID-19 due to its non-specific effects on the immune system. However, other complementary immune-induction methods at early stages of the disease may be needed. Here, the potentially preventive immunologic effects of BCG and influenza vaccination are compared with the immune response defects caused by aging and COVID-19. BCG co-administration with interferon-α/-β, or influenza vaccine is suggested to overcome its shortcomings in interferon signaling against COVID-19. However, further studies are highly recommended to assess the outcomes of such interventions considering their probable adverse effects especially augmented innate immune responses and overproduction of proinflammatory mediators.

Pneumococcal and Influenza Vaccination Rates and Pneumococcal Invasive Disease Rates Set Geographical and Ethnic Population Susceptibility to Serious COVID-19 Cases and Deaths

This study examines the relationship of pneumococcal vaccination rates, influenza, measles-mumps-rubella (MMR) diphtheria-tetanus-pertussis vaccinations (DTP), polio, Haemophilus influenzae type B (Hib), and Bacillus Calmette-Guerin (tuberculosis) vaccination rates to COVID-19 case and death rates for 51 nations that have high rates of COVID-19 testing and for which nearly complete childhood, at-risk adult and elderly pneumococcal vaccination data were available. The study is unique in a large number of nations examined, the range of vaccine controls, in testing effects of combinations of vaccinations, and in examining the relationship of COVID-19 and vaccination rates to invasive pneumococcal disease (IPD). Analysis of Italian regions and the states of the United States were also performed. Significant positive correlations were found between IPD (but not lower respiratory infections) and COVID-19 rates, while significant negative correlations were found between pneumococcal vaccination and COVID-19 rates. Influenza and MMR vaccination rates were negatively correlated with lower respiratory infection (LRI) rates and may synergize with pneumococcal vaccination rates to protect against COVID-19. Pneumococcal and influenza vaccination rates were independent of other vaccination rates. These results suggest that endemic rates of bacterial pneumonias, for which pneumococci are a sentinel, may set regional and national susceptibility to severe COVID-19 disease and death.

Tuberculosis vaccine BCG: the magical effect of the old vaccine in the fight against the COVID-19 pandemic

Bacillus Calmette-Guérin (BCG) is a live attenuated M. bovis vaccine that was developed about 100 years ago by Albert Calmette and Camille Guérin. Many countries have been using the vaccine for decades against tuberculosis (TB). The World Health Organization (WHO) recommends a single dose of BCG for infants in TB endemic as well as leprosy high risk countries, and globally almost 130 million infants are vaccinated yearly. The role of BCG is well known in reducing neonatal and childhood death rates. Epidemiological and retrospective cross-sectional studies demonstrated that the BCG vaccination protects the children against respiratory tract infections and lowers the risk of malaria in children. In addition, BCG enhances IFN-γ and IL-10 levels, thus providing immunity against respiratory tract infection even in elderly people. The BCG is also known to provide nonspecific innate immunity against viruses and parasites, through an innate immune mechanism termed ‘trained immunity’ and is defined as the immunological recall of the innate immune system by epigenetic reprogramming. Based on these studies it is suggested that the BCG has the potential to act as a protective agent against COVID-19. Further proven safety records of BCG in humans, its adjuvant activity and low-cost manufacturing make it an attractive option to stop the pandemic and reduce the COVID-19 related mortality. In this review we discuss the heterologous effects of BCG, induction of trained immunity and its implication in development of a potential vaccine against COVID-19 pandemic.

Bacille Calmette-Guérin (BCG) vaccine and potential cross-protection against SARS-CoV-2 infection - Assumptions, knowns, unknowns and need for developing an accurate scientific evidence base

After a century of controversies on its usefulness in protection against TB, underlying mechanisms of action, and benefits in various groups and geographical areas, the BCG vaccine is yet again a focus of global attention- this time due to the global COVID-19 pandemic caused by the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Recent studies have shown that human CD4+ and CD8+ T-cells primed with a BCG-derived peptide developed high reactivity to its corresponding SARS-CoV-2-derived peptide. Furthermore, BCG vaccine has been shown to substantially increase interferon-gamma (IFN-g) production and its effects on CD4+ T-cells and these non-specific immune responses through adjuvant effect could be harnessed as cross protection against severe forms of COVID-19.The completion of ongoing BGG trials is important as they may shed light on the mechanisms underlying BCG-mediated immunity and could lead to improved efficacy, increased tolerance of treatment, and identification of other ways of combining BCG with other immunotherapies.

Association between live childhood vaccines and COVID-19 outcomes: a national-level analysis

We investigated whether countries with higher coverage of childhood live vaccines [BCG or measles-containing-vaccine (MCV)] have reduced risk of coronavirus disease 2019 (COVID-19)-related mortality, while accounting for known systems differences between countries. In this ecological study of 140 countries using publicly available national-level data, higher vaccine coverage, representing estimated proportion of people vaccinated during the last 14 years, was associated with lower COVID-19 deaths. The associations attenuated for both vaccine variables, and MCV coverage became no longer significant once adjusted for published estimates of the Healthcare access and quality index (HAQI), a validated summary score of healthcare quality indicators. The magnitude of association between BCG coverage and COVID-19 death rate varied according to HAQI, and MCV coverage had little effect on the association between BCG and COVID-19 deaths. While there are associations between live vaccine coverage and COVID-19 outcomes, the vaccine coverage variables themselves were strongly correlated with COVID-19 testing rate, HAQI and life expectancy. This suggests that the population-level associations may be further confounded by differences in structural health systems and policies. Cluster randomised studies of booster vaccines would be ideal to evaluate the efficacy of trained immunity in preventing COVID-19 infections and mortality in vaccinated populations and on community transmission.

COVID-19 Infection and Previous BCG Vaccination Coverage in the Ecuadorian Population

The Bacillus Calmette–Guérin (BCG) is a well-known vaccine with almost a century of use, with the apparent capability to improve cytokine production and epigenetics changes that could develop a better response to pathogens. It has been postulated that BCG protection against SARS-CoV-2 has a potential role in the pandemic, through the presence of homologous amino acid sequences. To identify a possible link between BCG vaccination coverage and COVID-19 cases, we used official epidemic data and Ecuadorian Ministry of Health and Pan American Health Organization vaccination information. BCG information before 1979 was available only at a national level. Therefore, projections based on the last 20 years were performed, to compare by specific geographic units. We used a Mann–Kendall test to identify BCG coverage variations, and mapping was conducted with a free geographic information system (QGIS). Nine provinces where BCG vaccine coverage was lower than 74.25% show a significant statistical association (χ² Pearson’s = 4.800, df = 1, p = 0.028), with a higher prevalence of cases for people aged 50 to 64 years than in younger people aged 20 to 49 years. Despite the availability of BCG vaccination data and the mathematical models needed to compare these data with COVID-19 cases, our results show that, in geographic areas where BCG coverage was low, 50% presented a high prevalence of COVID-19 cases that were young; thus, low-coverage years were more affected.

An ecological study to evaluate the association of Bacillus Calmette-Guerin (BCG) vaccination on cases of SARS-CoV2 infection and mortality from COVID-19

As the SARS-CoV2 pandemic has progressed, there have been marked geographical differences in the pace and extent of its spread. We evaluated the association of BCG vaccination on morbidity and mortality of SARS-CoV2, adjusted for country-specific responses to the epidemic, demographics and health. SARS-CoV2 cases and deaths as reported by 31 May 2020 in the World Health Organization situation reports were used. Countries with at least 28 days following the first 100 cases, and available information on BCG were included. We used log-linear regression models to explore associations of cases and deaths with the BCG vaccination policy in each country, adjusted for population size, gross domestic product, proportion aged over 65 years, stringency level measures, testing levels, smoking proportion, and the time difference from date of reporting the 100th case to 31 May 2020. We further looked at the association that might have been found if the analyses were done at earlier time points. The study included 97 countries with 73 having a policy of current BCG vaccination, 13 having previously had BCG vaccination, and 11 having never had BCG vaccination. In a log-linear regression model there was no effect of country-level BCG status on SARS-CoV2 cases or deaths. Univariable log-linear regression models showed a trend towards a weakening of the association over time. We found no statistical evidence for an association between BCG vaccination policy and either SARS-CoV2 morbidity or mortality. We urge countries to rather consider alternative tools with evidence supporting their effectiveness for controlling SARS-CoV2 morbidity and mortality.

BCG, muramylpeptides, trained immunity (part I): linkages in the light of the COVID-19 pandemic

It has long been known that Bacillus CalmetteGurin (BCG) vaccine provides nonspecific protection against many non-mycobacterial infections, which has been discussed in the last decade through the prism of the concept of trained immunity. Within the framework of this concept, a persistent increase in resistance to various pathogens, which occurs after an infectious disease or exposure to certain microbial agents, is associated with epigenetic reprogramming of innate immune cells and their bone marrow progenitors. The COVID-19 pandemic has drawn attention of scientists and practitioners to BCG as an inducer of trained immunity. A number of epidemiological studies have suggested a negative association between the coverage of the population with BCG vaccination and the burden of SARS-CoV-2 infection. A series of independent clinical studies of the effectiveness of this vaccine in non-specific prevention of COVID-19 has been initiated in different countries. Recently, the key role of cytosolic NOD2 receptors in BCG-induced trained immunity has been proven. This actualizes the search for effective immunoactive preparations for prevention of respiratory infections in the pandemic among low molecular weight peptidoglycan fragments of the bacterial cell wall, muramylpeptides (MPs), which are known to be NOD2 agonists. The review highlights the proven and proposed linkages between BCG, MPs, NOD2 and trained immunity in the light of the COVID-19 pandemic. Analysis of the data presented indicates the prospects for preclinical and clinical studies of MPs as potential drugs for nonspecific prevention of SARS-CoV-2 infection and/or other respiratory infections in risk groups during the pandemic. First of all, attention should be paid to glucosaminylmuramyl dipeptide, approved for clinical use in Russia and a number of post-Soviet countries for the complex treatment and prevention of acute and recurrent respiratory infections.

BCG vaccine: Worrying proposal for COVID-19

Bacille Calmette-Guérin (BCG) vaccine is proven to be effective in protecting against severe tuberculosis. It has been suggested to be able to exert a non-specific beneficial effect as protection against other infectious diseases. The duration of protection against tuberculosis is estimated to be from 10 to 15 years, but the duration of the protection against other infections is not known, maybe up to 20 years, maybe much shorter than that. We don’t know it for sure. BCG induced trained immunity paradigm is based on experimental models, cohort studies with low number of individuals, and some epidemiological data in which other possible interfering factors are not controlled. The titles and scopes of scientific articles should be cautiously considered as they can promote indications of getting vaccinated or revaccinated with BCG, before its effectiveness is confirmed and recommendations are published. Besides, revaccination with BCG can put at serious risk patients with primary or secondary immunodeficiency. Maybe BCG vaccine is effective in preventing COVID-19 deaths or reducing its severity, but may the effect of this vaccine be relevant even with poor health politics and assistance? It is very difficult to compare the epidemiologic data about COVID-19 in different countries. There are countless factors, mainly social and related to the healthcare system, which can be more decisive than the hypothesis of trained immunity induced by BCG. Until now, we can say that BCG’s protective role is, at least, insufficient, given many other factors that corroborate SARS-CoV-2 infection and/or its severity.

Can BCG be useful to mitigate the COVID-19 pandemic? A Canadian perspective

There is ample evidence from in vitro, animal and human studies that the Bacillus Calmette-Guerin (BCG) vaccine epigenetically reprograms innate immunity to provide “off target” protection against pathogens other than mycobacteria. This process has been termed “trained immunity”. Although recent ecological studies suggested an association between BCG policies and the frequency or severity of COVID-19 in different countries, the interpretation of these results is challenging. For this reason, a case-control study aiming to test this hypothesis has been initiated in Quebec. Several phase III clinical trials are underway, including one in Canada, to assess the efficacy of BCG against SARS-CoV-2 infection (results expected in 2021). In the past, BCG has been widely used in Canada but current indications are restricted to high-risk individuals and communities experiencing TB outbreaks as well as for the treatment of bladder cancer. The potential implication of BCG as an interim measure to mitigate COVID-19 is the subject of widespread discussion in the scientific community and can be considered for the vulnerable population in Canada. To conclude, BCG vaccination should be placed on the agenda of research funding agencies, scientific advisory committees on immunization and federal/provincial/territorial public health authorities.

Is the tuberculosis vaccine BCG an alternative weapon for developing countries to defeat COVID-19?

Backgroud

Coronavirus disease (COVID-19) is a new respiratory infectious disease, and there is no vaccine currently. Previous studies have found that BCG vaccination can provide extensive protection against respiratory infectious diseases.

Methods

Herein, we obtained the latest data from the World Health Organization (WHO) as of August 12, 2020, and determined the relationship between three parameters (including the BCG vaccination coverage, human development index (HDI), and transmission classifications) and the incidence rate and mortality of COVID-19.

Results

The results showed that the morbidity and mortality of COVID-19 in countries with BCG vaccination recommendation were significantly lower than these in countries without BCG vaccination recommendation, and countries with lower HDI have lower morbidity and mortality. In addition, we also found that the mode of virus transmission is also related to the morbidity and mortality of COVID-19.

Conclusions

Although our data supports the hypothesis that BCG vaccination is beneficial in reducing the morbidity and mortality of COVID-19, the data supporting this result may be inaccurate due to many confounders such as PCR testing rate, population characteristics, and protection strategies, the reliability of this result still needs to be verified by clinical trials.

Bacille Calmette Guérin (BCG) and new TB vaccines: Specific, cross-mycobacterial and off-target effects

The Bacille Calmette Guérin (BCG) vaccine was developed over a century ago and has become one of the most used vaccines without undergoing a modern vaccine development life cycle. Despite this, the vaccine has protected many millions from severe and disseminated forms of tuberculosis (TB). In addition, BCG has cross-mycobacterial effects against non-tuberculous mycobacteria and off-target (also called non-specific or heterologous) effects against other infections and diseases. More recently, BCG's effects on innate immunity suggest it might improve the immune response against viral respiratory infections including SARS-CoV-2. New TB vaccines, developed over the last 30 years, show promise, particularly in prevention of progression to disease from TB infection in young adults. The role of BCG in the context of new TB vaccines remains uncertain as most participants included in trials have been previously BCG immunised. BCG replacement vaccines are in efficacy trials and these may also have off-target effects.

Association between live childhood vaccines and COVID-19 outcomes: a national-level analysis

We investigated whether countries with higher coverage of childhood live vaccines [BCG or measles-containing-vaccine (MCV)] have reduced risk of COVID-19 related mortality, accounting for known systems differences between countries. In this ecological study of 140 countries using publicly available national-level data, higher vaccine coverage, representing estimated proportion of people vaccinated during the last 15 years, was associated with lower COVID-19 deaths. The associations attenuated for both vaccine variables, and MCV coverage became no longer significant once adjusted for a validated summary score accounting for life expectancy and healthcare quality indicators, the Healthcare access and quality index (HAQI). The magnitude of association between BCG coverage and COVID-19 death rate varied according to HAQI, and MCV coverage had little effect on the association between BCG and COVID-19 deaths. While there are associations between live vaccine coverage and COVID-19 outcomes, the vaccine coverage variables themselves were strongly correlated with COVID-19 testing rate, HAQI, and life expectancy. This suggests that the population-level associations may be further confounded by differences in structural health systems and policies. Cluster randomized studies of booster vaccines would be ideal to evaluate the efficacy of trained immunity in preventing COVID-19 infections and mortality in vaccinated individuals and on community transmission.

Possible Cross-Reactivity between SARS-CoV-2 Proteins, CRM197 and Proteins in Pneumococcal Vaccines May Protect Against Symptomatic SARS-CoV-2 Disease and Death

Various studies indicate that vaccination, especially with pneumococcal vaccines, protects against symptomatic cases of SARS-CoV-2 infection and death. This paper explores the possibility that pneumococcal vaccines in particular, but perhaps other vaccines as well, contain antigens that might be cross-reactive with SARS-CoV-2 antigens. Comparison of the glycosylation structures of SARS-CoV-2 with the polysaccharide structures of pneumococcal vaccines yielded no obvious similarities. However, while pneumococcal vaccines are primarily composed of capsular polysaccharides, some are conjugated to cross-reacting material CRM197, a modified diphtheria toxin, and all contain about three percent protein contaminants, including the pneumococcal surface proteins PsaA, PspA and probably PspC. All of these proteins have very high degrees of similarity, using very stringent criteria, with several SARS-CoV-2 proteins including the spike protein, membrane protein and replicase 1a. CRM197 is also present in Haemophilus influenzae type b (Hib) and meningitis vaccines. Equivalent similarities were found at lower rates, or were completely absent, among the proteins in diphtheria, tetanus, pertussis, measles, mumps, rubella, and poliovirus vaccines. Notably, PspA and PspC are highly antigenic and new pneumococcal vaccines based on them are currently in human clinical trials so that their effectiveness against SARS-CoV-2 disease is easily testable.

COVID-19 Death and BCG Vaccination Programs Worldwide

Several clinical trials are being conducted worldwide to investigate the protective effect of the bacillus Calmette-Guérin (BCG) vaccine against death in healthcare providers who are working directly with coronavirus disease 2019 (COVID-19) patients. Clinical studies suggested that certain live vaccines, particularly the BCG vaccine, could reduce the mortality due to other diseases caused by non-targeted pathogens, most probably through the nonspecific effects (heterologous effects). By the end of May 2020, the available information on the COVID-19 pandemic indicated the great effect of the BCG vaccine in reducing the number of COVID-19 death cases. The occurrence of death due to COVID-19 was found to be 21-fold lower in countries with a national BCG vaccination policy than in countries without such a policy, based on the medians of COVID-19 death case per 1 million of the population in these two groups of countries (p<0.001, MannWhitney test). Therefore, it can be concluded that the early establishment of a BCG vaccination policy in any country is a key element in reducing the number of COVID-19 and tuberculosis death cases.

COVID-19 outbreak in Jordan: Epidemiological features, clinical characteristics, and laboratory findings

BACKGROUND

In March 2020, an outbreak of coronavirus 19 (COVID-19) was detected in the North of Jordan. This retrospective study is the first from Jordan to report the epidemiologic, clinical, laboratory, and radiologic characteristics of COVID-19 infected patients.

METHODS

All patients with laboratory-confirmed COVID-19 infection by RT-PCR in the North of Jordan admitted between March 15 and April 2, 2020 were included. The clinical features, radiological, and laboratory findings were reviewed.

RESULTS

Of 81 patients affected, 79 (97.5%) shared a common exposure to four recent travelers from endemic areas. The mean age was 40 years. Although about half (44 [54.3%]) were females, symptomatic patients were mostly females (75%). The most common presenting symptoms were nasal congestion, sore throat and dry cough. Less than one-third (31%) had chronic diseases. Although 84% of patients reported receiving Bacille Calmette-Guérin (BCG) vaccination, more asymptomatic patients had BCG than symptomatic (p = 0.017). Almost all patients (97.5%) had an elevated D-dimer level. Erythrocyte sedimentation rate (ESR) and c-reactive protein were elevated in 50% and 42.7% of patients, respectively. High ESR found to be the predictor of abnormal chest radiograph observed in 13 (16%) patients with OR of 14.26 (95% CI 1.37-147.97, p = 0.026).

CONCLUSIONS

An outbreak of COVID-19 infection in northern Jordan affected more females and relatively young individuals and caused mainly mild illnesses. The strict outbreak response measures applied at early stages probably contributed to the lenient nature of this outbreak, but the contribution of other factors to such variability in COVID-19 presentation is yet to be explained.

COVID-19 in Light of Seasonal Respiratory Infections

A wide diversity of zoonotic viruses that are capable of overcoming host range barriers facilitate the emergence of new potentially pandemic viruses in the human population. When faced with a new virus that is rapidly emerging in the human population, we have a limited knowledge base to work with. The pandemic invasion of the new SARS-CoV-2 virus in 2019 provided a unique possibility to quickly learn more about the pathogenesis of respiratory viruses. In this review, the impact of pandemics on the circulation of seasonal respiratory viruses is considered. The emergence of novel respiratory viruses has often been accompanied by the disappearance of existing circulating strains. Some issues arising from the spread of pandemic viruses and underlying the choices of a strategy to fight the coronavirus infection are discussed.