Molecular characterization of influenza B virus outbreak on a cruise ship in Brazil 2012

Investigation of the use of PCR testing prior to ship boarding to prevent the spread of SARS-CoV-2 from urban areas to less-populated remote islands

Preventing coronavirus disease (COVID-19) outbreaks and the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from urban areas to less-populated remote islands, many of which may have weak medical systems, is an important issue. Here, we evaluated the usefulness of pre-boarding, saliva-based polymerase chain reaction (PCR) screening tests to prevent the spread of SARS-CoV-2 from Tokyo to the remote island of Chichijima. The infection rate on the island during the study period from September 1, 2020 to March 21, 2021 was 0.015% (2/13,446). Of the 8,910 individuals tested before ship boarding, seven tested positive for COVID-19 (PCR tests of saliva samples). One was confirmed positive by subsequent confirmatory nasopharyngeal swab testing. Based on the testing results, positive cases were denied entry onto the ship to prevent the spread of COVID-19 from Tokyo to Chichijima. This study demonstrated that implementing pre-boarding PCR screening tests is a useful strategy that can be applied to other remote islands with vulnerable medical systems.

Reconstitution of Oseltamivir Capsules for Pediatric Use on a Long-Term Cruise: A Treatment Option

Influenza is a concerning disease in terms of risk management for cruise passengers during a voyage. Currently, cruise passengers include children in addition to elderly people. Oral oseltamivir can be used to treat pediatric influenza. In addition, early antiviral treatment may reduce the spread of influenza on board. However, the capsule form of oseltamivir is not of the recommended dosage for children. In this report, we describe 2 siblings who acquired influenza during travel on a world cruise ship and were treated with decapsulated oseltamivir. The siblings' mother was instructed to decapsulate a 75 mg oseltamivir capsule, suspend the powder in 15 mL of water (5 mg·mL^-1), stir well, and administer the required amount of medicine orally to each patient using a syringe. Both patients recovered successfully with no complications. The presented case suggests that suspending decapsulated oseltamivir in water and measuring the required amount with a syringe for orally administration to children with influenza can be a safe treatment strategy in resource-limited settings.

SARS-CoV-2 shedding and seroconversion among passengers quarantined after disembarking a cruise ship: a case series

Background

A cruise ship is a closed-off environment that simulates the basic functioning of a city in terms of living conditions and interpersonal interactions. Thus, the Diamond Princess cruise ship, which was quarantined because of an onboard outbreak of COVID-19 in February, 2020, provides an opportunity to define the shedding pattern of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and patient antibody responses before and after the onset of symptoms.

Methods

We recruited adult (≥18 years) passengers from Hong Kong who had been on board the Diamond Princess cruise ship docked in Yokohama, Japan in February, 2020. All participants had been found to be negative for SARS-CoV-2 by RT-PCR 4 days before disembarking and were transferred to further quarantine in a public estate in Hong Kong, where they were recruited. Participants were prospectively screened by quantitative RT-PCR (RT-qPCR) of nasopharyngeal and throat swabs, and serum IgG and IgM against internal nucleoprotein and the surface spike receptor-binding protein (RBD) of SARS-CoV-2 at baseline (upon entering quarantine) and on days 4, 8, and 12 of quarantine.

Findings

On Feb 22, 2020, 215 adults were recruited, of whom nine (4%; 95% CI 2–8) were positive for SARS-CoV-2 by RT-qPCR or serology and were hospitalised. Of these nine patients, nasopharyngeal swab RT-qPCR was positive in eight patients (89%; 57–99) at baseline. All nine patients were positive for anti-RBD IgG by day 8. Eight (89%; 57–99) were simultaneously positive for nasopharyngeal swab RT-PCR and anti-RBD IgG. One patient who was positive for anti-RBD IgG and had a negative viral load had multifocal peripheral ground-glass changes on high-resolution CT that were typical of COVID-19. Five patients (56%; 27–81) with ground-glass changes on high-resolution CT were found to have higher anti-nucleoprotein-IgG OD values on day 8 and 12 and anti-RBD IgG OD value on day 12 than patients without ground-glass changes. Six (67%; 35–88) patients remained asymptomatic throughout the 14-day quarantine period.

Interpretation

Patients with COVID-19 can develop asymptomatic lung infection with viral shedding and those with evidence of pneumonia on imaging tend to have an increased antibody response. Positive IgG or IgM confirmed infection of COVID-19 in both symptomatic and asymptomatic patients. A combination of RT-PCR and serology should be implemented for case finding and contact tracing to facilitate early diagnosis, prompt isolation, and treatment.

Funding

Shaw Foundation Hong Kong; Sanming-Project of Medicine (Shenzhen); High Level-Hospital Program (Guangdong Health Commission).

COVID-19 outbreak on the Diamond Princess cruise ship: estimating the epidemic potential and effectiveness of public health countermeasures

BACKGROUND

Cruise ships carry a large number of people in confined spaces with relative homogeneous mixing. On 3 February, 2020, an outbreak of COVID-19 on cruise ship Diamond Princess was reported with 10 initial cases, following an index case on board around 21-25th January. By 4th February, public health measures such as removal and isolation of ill passengers and quarantine of non-ill passengers were implemented. By 20th February, 619 of 3700 passengers and crew (17%) were tested positive.

METHODS

We estimated the basic reproduction number from the initial period of the outbreak using SEIR models. We calibrated the models with transient functions of countermeasures to incidence data. We additionally estimated a counterfactual scenario in absence of countermeasures, and established a model stratified by crew and guests to study the impact of differential contact rates among the groups. We also compared scenarios of an earlier versus later evacuation of the ship.

RESULTS

The basic reproduction rate was initially 4 times higher on-board compared to the ${R}_0$ in the epicentre in Wuhan, but the countermeasures lowered it substantially. Based on the modeled initial ${R}_0$ of 14.8, we estimated that without any interventions within the time period of 21 January to 19 February, 2920 out of the 3700 (79%) would have been infected. Isolation and quarantine therefore prevented 2307 cases, and lowered the ${R}_0$ to 1.78. We showed that an early evacuation of all passengers on 3 February would have been associated with 76 infected persons in their incubation time.

CONCLUSIONS

The cruise ship conditions clearly amplified an already highly transmissible disease. The public health measures prevented more than 2000 additional cases compared to no interventions. However, evacuating all passengers and crew early on in the outbreak would have prevented many more passengers and crew from infection.

COVID-19 outbreak on the Diamond Princess cruise ship: estimating the epidemic potential and effectiveness of public health countermeasures

BACKGROUND

Cruise ships carry a large number of people in confined spaces with relative homogeneous mixing. On 3 February, 2020, an outbreak of COVID-19 on cruise ship Diamond Princess was reported with 10 initial cases, following an index case on board around 21-25th January. By 4th February, public health measures such as removal and isolation of ill passengers and quarantine of non-ill passengers were implemented. By 20th February, 619 of 3700 passengers and crew (17%) were tested positive.

METHODS

We estimated the basic reproduction number from the initial period of the outbreak using SEIR models. We calibrated the models with transient functions of countermeasures to incidence data. We additionally estimated a counterfactual scenario in absence of countermeasures, and established a model stratified by crew and guests to study the impact of differential contact rates among the groups. We also compared scenarios of an earlier versus later evacuation of the ship.

RESULTS

The basic reproduction rate was initially 4 times higher on-board compared to the ${R}_0$ in the epicentre in Wuhan, but the countermeasures lowered it substantially. Based on the modeled initial ${R}_0$ of 14.8, we estimated that without any interventions within the time period of 21 January to 19 February, 2920 out of the 3700 (79%) would have been infected. Isolation and quarantine therefore prevented 2307 cases, and lowered the ${R}_0$ to 1.78. We showed that an early evacuation of all passengers on 3 February would have been associated with 76 infected persons in their incubation time.

CONCLUSIONS

The cruise ship conditions clearly amplified an already highly transmissible disease. The public health measures prevented more than 2000 additional cases compared to no interventions. However, evacuating all passengers and crew early on in the outbreak would have prevented many more passengers and crew from infection.

Haemagglutinin and neuraminidase sequencing delineate nosocomial influenza outbreaks with accuracy equivalent to whole genome sequencing

OBJECTIVES

We describe haemagglutinin (HA) and neuraminidase (NA) sequencing in an apparent cross-site influenza A(H1N1) outbreak in renal transplant and haemodialysis patients, confirmed with whole genome sequencing (WGS).

METHODS

Isolates were sequenced from influenza positive individuals. Phylogenetic trees were constructed using HA and NA sequencing and subsequently WGS. Sequence data was analysed to determine genetic relatedness of viruses obtained from inpatient and outpatient cohorts and compared with epidemiological outbreak information.

RESULTS

There were 6 patient cases of influenza in the inpatient renal ward cohort (associated with 3 deaths) and 9 patient cases in the outpatient haemodialysis unit cohort (no deaths). WGS confirmed clustered transmission of two genetically different influenza A(H1N1)pdm09 strains initially identified by analysis of HA and NA genes. WGS took longer, and in this case was not required to determine whether or not the two seemingly linked outbreaks were related.

CONCLUSION

Rapid sequencing of HA and NA genes may be sufficient to aid early influenza outbreak investigation making it appealing for future outbreak investigation. However, as next generation sequencing becomes cheaper and more widely available and bioinformatics software is now freely accessible next generation whole genome analysis may increasingly become a valuable tool for real-time Influenza outbreak investigation.

An epidemiological study of rates of illness in passengers and crew at a busy Caribbean cruise port

Background

The Caribbean has one of the largest cruise ship industries in the world, with close to 20 million visitors per year. The potential for communicable disease outbreaks on vessels and the transmission by ship between countries is high. Barbados has one of the busiest ports in the Caribbean. Our aim was to describe and analyse the epidemiology of illnesses experienced by passengers and crew arriving at the Bridgetown Port, Barbados between 2009 and 2013.

Methods

Data on the illnesses recorded were extracted from the passenger and crew arrival registers and passenger and crew illness logs for all ships and maritime vessels arriving at Barbados’ Ports and passing through its territorial waters between January 2009 and December 2013. Data were entered into an Epi Info database and most of the analysis undertaken using Epi Info Version 7. Rates per 100,000 visits were calculated, and confidence intervals on these were derived using the software Openepi.

Results

There were 1031 cases of illness from over 3 million passenger visits and 1 million crew visits during this period. The overall event rate for communicable illnesses was 15.7 (95 % CI 14.4–17.1) per 100,000 passengers, and for crew was 24.0 (21.6–26.6) per 100, 000 crew. Gastroenteritis was the predominant illness experienced by passengers and crew followed by influenza. The event rate for gastroenteritis among passengers was 13.7 (12.5–15.0) per 100,000 and 14.4 (12.6, 16.5) for crew. The event rate for non-communicable illnesses was 3.4 per 100,000 passengers with myocardial infarction being the main diagnosis. The event rate for non-communicable illnesses among crew was 2.1 per 100,000, the leading cause being injuries.

Conclusions

The predominant illnesses reported were gastroenteritis and influenza similar to previous published reports from around the world. This study is the first of its type in the Caribbean and the data provide a baseline for future surveillance and for comparison with other countries and regions.

Patterns of influenza B circulation in Brazil and its relevance to seasonal vaccine composition

Data on the burden of disease and circulation patterns of influenza B lineages for Brazil are limited. This review aims to describe the pattern of influenza B occurrence in Brazil to have a better understanding of its epidemiology and its relevance when considering seasonal influenza vaccine composition. A review of the data including analysis of international and local surveillance data as well as information from online search of databases using Medical Subject Headings terms in conjunction with screening of abstracts from scientific events was performed. Based on international epidemiologic surveillance data, moderate levels of influenza B disease (19%; 2006-2014) were observed. Of these nine years, it was possible to compare data from three years (2007, 2008 and 2013) which have information on the circulating influenza B lineage. Co-circulation of influenza B lineages was observed in all these three influenza seasons, of which, during one season, a high degree of mismatch between the vaccine lineage and the predominant circulating lineage (91.4% [2013]) was observed. Local surveillance data reveal a distinct and dynamic distribution of respiratory viruses over the years. Data from published literature and abstracts show that influenza B is a significant cause of disease with an unpredictable circulation pattern and showing trends indicating reemergence of the B/Victoria lineage. The abstracts report notable levels of co-circulation of both influenza B lineages (2000-2013). Mismatch between the Southern hemisphere vaccine and the most prevalent circulating viruses in Brazil were observed in five influenza seasons. The evidence on co-circulation of two influenza B lineages and mismatched seasons in Brazil indicates the benefit of quadrivalent influenza vaccines in conferring broader seasonal influenza protection. Additionally, improving influenza surveillance platforms in Brazil is important for monitoring disease trends and the impact of introducing seasonal influenza vaccination.

Circulation of influenza B lineages in northern Viet Nam, 2007-2014

INTRODUCTION

Influenza B viruses circulate throughout Viet Nam, and their activities vary by region. There have been two antigenically distinct lineages of influenza B viruses co-circulating in the past 20 years; however, only one lineage is selected as a component of contemporary trivalent seasonal influenza vaccines. To improve the understanding of circulating influenza B lineages and influenza vaccine mismatches, we report the virus lineages circulating in northern Viet Nam over an eight-year period (2007-2014).

METHODS

Lineages of 331 influenza B viruses were characterized by haemagglutination inhibition assay against standard reference ferret (Yamagata) and sheep (Victoria) antisera. Sequence analysis of the haemagglutinin gene was performed in 64 selected influenza B isolates.

RESULTS

The proportion of influenza B lineages changed by year. The Yamagata lineage predominated in 2007, 2008 and 2012; the Victoria lineage predominated in 2009-2014 except 2012. The two lineages showed continuous evolution over time. The Northern Hemisphere's influenza vaccine components were mismatched with the predominant circulating viruses in 2007, 2009 and 2014.

DISCUSSION

The seasonality of influenza B activity is more variable in tropical and subtropical regions than in temperate zones. Our data showed a common co-circulation of both influenza B lineages in northern Viet Nam, and it was difficult to predict which one was the predominant lineage. Quadrivalent influenza vaccines containing both lineages may improve the effectiveness of influenza vaccine programmes in the future.