Global seroprevalence of SARS-CoV-2 antibodies: A systematic review and meta-analysis

BACKGROUND

Many studies report the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies. We aimed to synthesize seroprevalence data to better estimate the level and distribution of SARS-CoV-2 infection, identify high-risk groups, and inform public health decision making.

METHODS

In this systematic review and meta-analysis, we searched publication databases, preprint servers, and grey literature sources for seroepidemiological study reports, from January 1, 2020 to December 31, 2020. We included studies that reported a sample size, study date, location, and seroprevalence estimate. We corrected estimates for imperfect test accuracy with Bayesian measurement error models, conducted meta-analysis to identify demographic differences in the prevalence of SARS-CoV-2 antibodies, and meta-regression to identify study-level factors associated with seroprevalence. We compared region-specific seroprevalence data to confirmed cumulative incidence. PROSPERO: CRD42020183634.

RESULTS

We identified 968 seroprevalence studies including 9.3 million participants in 74 countries. There were 472 studies (49%) at low or moderate risk of bias. Seroprevalence was low in the general population (median 4.5%, IQR 2.4-8.4%); however, it varied widely in specific populations from low (0.6% perinatal) to high (59% persons in assisted living and long-term care facilities). Median seroprevalence also varied by Global Burden of Disease region, from 0.6% in Southeast Asia, East Asia and Oceania to 19.5% in Sub-Saharan Africa (p<0.001). National studies had lower seroprevalence estimates than regional and local studies (p<0.001). Compared to Caucasian persons, Black persons (prevalence ratio [RR] 3.37, 95% CI 2.64-4.29), Asian persons (RR 2.47, 95% CI 1.96-3.11), Indigenous persons (RR 5.47, 95% CI 1.01-32.6), and multi-racial persons (RR 1.89, 95% CI 1.60-2.24) were more likely to be seropositive. Seroprevalence was higher among people ages 18-64 compared to 65 and over (RR 1.27, 95% CI 1.11-1.45). Health care workers in contact with infected persons had a 2.10 times (95% CI 1.28-3.44) higher risk compared to health care workers without known contact. There was no difference in seroprevalence between sex groups. Seroprevalence estimates from national studies were a median 18.1 times (IQR 5.9-38.7) higher than the corresponding SARS-CoV-2 cumulative incidence, but there was large variation between Global Burden of Disease regions from 6.7 in South Asia to 602.5 in Sub-Saharan Africa. Notable methodological limitations of serosurveys included absent reporting of test information, no statistical correction for demographics or test sensitivity and specificity, use of non-probability sampling and use of non-representative sample frames.

DISCUSSION

Most of the population remains susceptible to SARS-CoV-2 infection. Public health measures must be improved to protect disproportionately affected groups, including racial and ethnic minorities, until vaccine-derived herd immunity is achieved. Improvements in serosurvey design and reporting are needed for ongoing monitoring of infection prevalence and the pandemic response.

Vancomycin relieves mycophenolate mofetil-induced gastrointestinal toxicity by eliminating gut bacterial β-glucuronidase activity

Mycophenolate mofetil (MMF) is commonly prescribed and has proven advantages over other immunosuppressive drugs. However, frequent gastrointestinal side effects through an unknown mechanism limit its use. We have found that consumption of MMF alters the composition of the gut microbiota, selecting for bacteria expressing the enzyme β-glucuronidase (GUS) and leading to an up-regulation of GUS activity in the gut of mice and symptomatic humans. In the mouse, vancomycin eliminated GUS-expressing bacteria and prevented MMF-induced weight loss and colonic inflammation. Our work provides a mechanism for the toxicity associated with MMF and a future direction for the development of therapeutics.

Association between tumour necrosis-α gene polymorphisms and acne vulgaris in a Pakistani population

BACKGROUND

The cytokine tumour necrosis factor (TNF)-α is a well-studied potent candidate mediator that is systemically involved in a variety of inflammatory diseases. Several single nucleotide polymorphisms (SNPs) of the TNF-α gene have been studied with regard the pathogenesis of acne vulgaris, but the results have been inconclusive.

AIM

This case-control study investigated the association of the TNF -308 G>A and -238 G>A SNPs with acne vulgaris in a high-risk Pakistani population.

METHODS

In total, 160 healthy controls and 140 patients with acne were enrolled in this study. Polymorphisms were determined by PCR and restriction fragment length polymorphism analysis.

RESULTS

Our data showed that the TNF -308 G>A and TNF -238 G>A SNPs were present at a significantly higher rate in cases than in controls (P < 0.01 and P < 0.02; respectively). There was a significant difference between the G and A alleles from patients with acne and controls for -308 G>A (OR = 1.5, 95% CI = 1.07-2.19, P < 0.02) and -238 G>A (OR=1.6, 95% CI = 1.06-2.44, P = 0.02) genotype. Moreover, the severity of acne was significantly associated with TNF genotype (TNF -308 G>A: χ² = 34.6, P < 0.001; TNF -238 G>AL χ² = 12.9, P < 0.01).

CONCLUSION

Our data suggest that the TNF -308 G>A and TNF -238 G>A SNPs may contribute to the pathogenesis of acne in the study population. Furthermore, patients with severe acne showed an increased frequency of mutant TNF genotypes at -308 and -238 compared with patients with less severe acne.

Intraoperative radiotherapy given as a boost after breast-conserving surgery in breast cancer patients

Conventional radiotherapy after breast-conserving therapy is confined to 50-55 Gy external beam radiation therapy (EBRT) to the whole breast and 10-16 Gy external boost radiation to the tumour bed or brachytherapy to the tumour bed. Local recurrence rate after breast-conserving surgery varies between 5 and 18%. External boost radiation can partially miss the tumour bed and therefore can result in local failure. Intra-operative radiotherapy (IORT) as a high precision boost can prevent a 'geographical miss'. From October 1998 to December 2000, 156 patients with stage I and stage II breast cancer were operated upon in a dedicated IORT facility. After local excision of the tumour, the tumour bed was temporarily approximated by sutures to bring the tissue in the radiation planning target volume. A single dose of 9 Gy was applied to the 90% reference isodose with energies ranging from 4 to 15 MeV, using round applicator tubes 4-8 cm in diameter. After wound healing, the patients received additional 51-56 Gy EBRT to the whole breast. No acute complications associated with IORT were observed. In 5 patients, a secondary mastectomy had to be performed because of tumour multicentricity in the final pathological report or excessive intraductal component. 2 patients developed rib necroses. In 7 patients, wound healing problems occurred. After a mean follow-up of 18 months, no local recurrences were observed. Cosmesis of the breast was very good and comparable to patients without IORT. Preliminary data suggest that IORT given as a boost after breast-conserving surgery could be a reliable alternative to conventional postoperative fractionated boost radiation by accurate dose delivery and avoiding geographical misses, by enabling smaller treatment volumes and complete skin-sparing and by reducing postoperative radiation time by 7-14 days.

Nitric oxide synthase, cyclooxygenase 2, and vascular endothelial growth factor in the angiogenesis of non-small cell lung carcinoma

We have investigated the hypothesis that nitric oxide synthase (NOS2), cyclooxygenase-2 (COX2), and vascular endothelial growth factor (VEGF) protein levels individually demonstrate a direct correlation with microvessel density (MVD) and clinical outcome in human non-small cell lung cancer (NSCLC). Furthermore, we hypothesized that MVD may explain the propensity of certain histological lung cancer subtypes for early metastasis via a hematological route. Immunohistochemically, we studied the protein expression levels of NOS2, COX2, and VEGF and MVD by counting CD31-reactive blood vessels (BVs) in 106 surgically resected NSCLC specimens. NOS2, COX2, and VEGF immunoreactivity were observed in 48, 48, and 58%, respectively, of the study subjects, and their levels correlated with MVD at the tumor-stromal interphase (P < or = 0.001). More adenocarcindmas and large cell carcinomas displayed overexpression of NOS2 when compared with squamous cell carcinoma (SCC; r = 0.44; P < 0.001). NOS2 and COX2 levels were found to correlate positively with VEGF status (r = 0.44; P < 0.001, 0.01, and 0.03, respectively). These results attest to the significant interaction of these factors in the angiogenesis of NSCLC. Although neither angiogenic factors nor MVD correlated with patient survival, the latter correlated with tumor clinical stage in both squamous (SCC; 73 BVs/mm2) and non-SCC (78 BVs/mm2) tumors. These results indicate that angiogenesis is a complex process that involves multiple factors including NOS2, COX2, and VEGF. Furthermore, the role of angiogenesis in the biology of various histological lung cancer types may be different. The complexity of angiogenesis may explain the modest results observed in antiangiogenesis therapy that target a single protein.

[Long-term tumor control and fertility after para-aortic limited radiotherapy of stage I seminoma]

PURPOSE

To review patterns of relapse in a long-term analysis of patients with Stage I seminoma treated by orchidectomy and radiotherapy to the paraaortic lymph nodes only and to follow follicle stimulating hormone (FSH) levels dependent on testicular scatter dose.

PATIENTS AND METHODS

From 1980 to 1995, 58 patients with Stage I seminoma received elective radiotherapy to the paraaortic lymph nodes only (Th12 to L4), with a mean total dose of 28.07 Gy (+/- 2.2 SD), using fractional doses between 1.5 and 2 Gy (mean 1.62 Gy +/- 0.083 SD). Since 1989, testicular scatter doses were measured routinely by in-vivo thermoluminescent dosimetry (TLD) in 45 patients. In 26 patients with normal pre-treatment values of FSH, FSH-levels were repeatedly controlled after radiotherapy in order to evaluate any radiation-induced sequelae.

RESULTS

During a mean observation period of 69.4 months (range 30 to 210), 2 out of 57 patients (3.5%) developed regional recurrences in the ipsilateral pelvic lymph nodes 14 months and 5 years after radiotherapy, respectively. One patient was lost to follow-up. The relapse-free survival rate at 5 years was 96.5% after radiotherapy alone. After salvage chemotherapy, both relapse-free survival and overall survival rates come to 100%. The mean testicular scatter dose in 45 patients was 0.22 Gy (+/- 0.087 SD). Seven out of 26 patients (26.9%) developed a transient increase of FSH-levels, reaching peak values at 4.2 months and returning to normal ranges within 18 months after radiotherapy. Below 0.2 Gy, no effect on FSH was observed. Testicular scatter doses showed no clear correlation to FSH risings (Figure 1).

CONCLUSION

After exclusive paraaortic radiation of Stage I seminoma, even at follow-up periods in excess of 5 years the incidence of pelvic lymph node relapses remains below 4%. However, there seems to be a small potential for the development of late recurrences. With limited radiotherapy, permanent radiation-induced effects on the remaining testicle are very unlikely.

Radiotherapy for lung cancer: target splitting by asymmetric collimation enables reduction of radiation doses to normal tissues and dose escalation

PURPOSE

This study was performed to develop a method of reducing the radiation doses to normal thoracic tissues, increasing the target dose, especially in the primary radiotherapy of non-small cell lung cancer (NSCLC), and to evaluate acute/subacute toxicity of dose escalation.

METHODS AND MATERIALS

From December 1195 to March 1998, the technique of target splitting has been applied to 58 patients. In this period, 30 patients were treated with doses > 80 Gy (ICRU-specification, mean 85.1 Gy, range 80. 1-90.2 Gy). The target volume is split into a cranial part (e.g., upper mediastinum) and a caudal part (e.g., primary tumor and middle mediastinum). Both volumes are planned and treated independently, using conformal irradiation techniques for both parts with half-collimated fields to prevent over- or underdosage in the junction plane. After fine-adjustment of the jaws, a verification film, exposed in a polymethylmethacrylate (PMMA) phantom, demonstrates the homogeneity of dose in the entire target volume. For comparison with conventional techniques, planning to identical doses is performed for 5 patients. Dose-volume histograms (DHVs) for normal lung tissue are presented for both methods.

RESULTS

The irradiated volume of normal tissue of the ipsilateral lung can be lowered at dose levels > or = 65, > or =45 Gy, and > or = 20 Gy to values of 37% (range 25-54%), 49% (range 46-54%), and 86% (range 55-117%), respectively. Other organs at risk, such as heart or esophagus, can also be spared significantly. Only 1 patient showed a transient grade 3 toxicity (pneumonitis), and there where no grade 4 acute/subacute side-effects. Two patients with Stage III A central tumors in close proximity to the large vessels died due to a pulmonary hemorrhage 2 and 4 months after therapy, respectively. No patient developed esophagitis. Antimycotic prophylaxis for esophagitis and posttherapeutic steroid prophylaxis for pneumonitis for several weeks were routinely used.

CONCLUSION

The technique of target splitting by asymmetric collimation helps to increase conformation, and thus enhances the sparing of normal tissues. It can be used whenever there is a marked difference in the shape of the planning target volume (PTV) in a cranio-caudal direction. This technique can principally be handled with 2D-planning systems, because it is coplanar. We consider target splitting as an important tool for dose escalation in the primary radiotherapy of NSCLC, that should also be used for other lung cancer patients necessitating moderate doses only.

Risk factors associated with the recall of respiratory diseases in the Ecuadorian children

Risk factors associated with the recall of a recent episode of acute respiratory infection (ARI) were evaluated in 1,553 Ecuadorian preschool children enrolled into a cross-sectional health and nutrition survey. In a univariate analysis, ARI recall was significantly higher in children living in low altitude regions (Relative Risk, RR = 2.4), in younger children (RR = 1.6), in children from larger families (RR = 1.3), in children with diarrhoea recall (RR = 1.9), in children served with poor quality drinking water (RR = 1.3) and in anaemic children (RR = 1.2) than that in the appropriate control groups. After taking into account the confounding effect of altitude, no association was found between ARI recall and low height-for-age values. Stepwise logistic regression analysis identified living in low altitude regions, diarrhoea recall, and younger age as independent factors associated with a higher recall of ARI. In contrast to the recall of acute diarrhoea, no association between ARI recall and nutritional status was found. The impact of nutritional interventions in children from developing countries may be greater on enteric than on respiratory diseases.

Nutritional and environmental risk factors for diarrhoeal diseases in Ecuadorian children

Risk factors associated with diarrhoea, based on the recall of a recent episode were evaluated from a cross-sectional national nutrition and health study in 1,620 Ecuadorian children less than 5 years old. Prevalence of diarrhoea varied with the age of the children; 6- to 23-months-old children showed the highest prevalence. In this age range the prevalence of diarrhoea was significantly associated with hygienic factors (quality of drinking water, sanitation and refuse system), but not with demographic factors (sex, altitude, population density, family size). The nutritional status of the children was determined by anthropometry and blood chemistry. After stratification for sanitation levels, a low weight-for-age Z-score and low serum retinol and zinc concentrations showed a statistically significant (p < or = 0.06) association with diarrhoea prevalence only in children living under better hygienic conditions. Multivariate analysis revealed significant associations between both sanitation levels and nutritional level as defined by anthropometry, but not by blood chemistry, and diarrhoea prevalence.

Epidemiological analysis of serologically determined rotavirus and enterotoxigenic Escherichia coli infections in Ecuadorian children

The statistical association of rotavirus- and enterotoxigenic Escherichia coli-specific serum antibody with demographic and hygienic factors was tested in Ecuadorian children enrolled in a cross-sectional survey. In 7- to 10-month-old children, enterotoxigenic E. coli-specific antibody was associated (P less than 0.05) with poor drinking water quality, lack of a sewage system, and feeding of supplementary food. In 7- to 14-month-old children, rotavirus-specific antibody was associated only with family size but notably not with hygienic factors.

Antibodies to seven rotavirus serotypes in cord sera, maternal sera, and colostrum of German women

Forty percent of colostrum samples from German women showed neutralizing antibody titers of greater than or equal to 50 to rotavirus (RV) serotypes 1, 3, 4, and 6. Antibody to serotypes 2, 8, and 9 was less prevalent. Titers are, however, too low to indicate an important effect of colostrum on the RV vaccine take rate. On the other hand, about 50% of the cord serum samples showed high neutralizing-antibody titers to serotypes 1, 3, and 4, which could interfere with the take rate of RV vaccines based on these serotypes in very young infants.

Infectious gastroenteritis does not act as a triggering mechanism for the synthesis of serum IgG antibody to beta-lactoglobulin

beta-Lactoglobulin (BLG)-specific serum IgG antibody was measured by enzyme-linked immunosorbent assay in 1,392 serum samples from newborn to 5-year-old Ecuadorian children enrolled into a representative nutrition and health survey. At a 1:100 serum dilution, 62% of the children showed specific antibody (blank-corrected optical density greater than or equal to 0.1). This prevalence did not change with increasing age. More specifically, we did not observe a prevalence or titer increase of BLG-specific antibody in age groups where the majority of these Ecuadorian children experienced infection with rotavirus (8-24-month age groups) and enterotoxigenic Escherichia coli (8-12-month age group). In addition, BLG-specific antibody did not differ between children who did or did not experience an episode of diarrhea 15 days before blood sampling. We observed a small but statistically significant difference in BLG-specific antibody between subsamples of Ecuadorian children regularly or only occasionally ingesting milk. Titers were higher in the group consuming more milk.

A reassessment of risk factors for neonatal tetanus

A hospital-based case-control study was conducted to further examine the risk factors for neonatal tetanus (NNT) in the North-west Frontier Province of Pakistan. Three control infants were concurrently evaluated for each of 102 consecutively diagnosed NNT cases hospitalized over an 8-week period. Application of clarified butter (ghee) during the first few days of life was shown to be a significant risk factor, confirming our previously reported finding. However, the risk appeared to be limited to ghee made in the home from cow's milk. The tool used to cut the umbilical cord was again refuted to be a risk factor; application of topical antibiotics conferred significant protection. Multivariate analysis of the matched data showed that delivery by persons with academic training (physicians, nurses, and lady health visitors) was also protective. Mothers with a past history of NNT babies were shown to have a significantly increased risk, and accounted for more than one-third of all cases in the present study. The findings suggest possible ways to augment the effectiveness of NNT elimination programmes.

[Control measurements with TLD-100 sticks for selected radiation fields]

The influence exerted on dose distribution by the specific mass of the material is investigated for irradiation planning on the basis of CT matrices. It is shown that the specific masses of the Alderson phantom actually differ from those calculated by conversion of CT figures. In some planning systems, the conversion of CT figures into specific masses is the only parameter which can be verified by the user. Furthermore, the results of control measurements on the irradiation planning with the system Sidos-U (Siemens Company) are presented.

Ghee applications to the umbilical cord: a risk factor for neonatal tetanus

A case-control study was done to elucidate risk factors for neonatal tetanus (NNT) in rural Pakistan; three controls were selected for each of the 69 cases. Factors commonly believed to be associated with NNT, such as the tool used to cut the umbilical cord and the method of preparing the tool, were not confirmed as risk factors. However, applying ghee to the wound stump was. New prevention opportunities deriving from the finding should be pursued aggressively while efforts to develop effective delivery systems to immunise mothers against tetanus continue, a task made difficult by sociocultural factors.

[Radiation dosage and clinical value of conventional tomography and high resolution computerized tomography of the nose and ear]

Hypocycloidal (frontal and temporal) tomography of the base of the skull is compared with high resolution computed tomography (HR-CT) with respect to dose and clinical usefulness. In most cases HR-CT is indicated because of its better density resolution in comparison with conventional hypocycloidal tomography. As the X-ray beam is directed at the slice plane the dosage is noticeably less than when using conventional tomography. Slice thickness depends on the required geometric resolution. This is an additional factor in radiation protection.

Inadequacy of conventional computerized tomography scans for treatment planning of tangential breast (chest wall) fields

The use of transverse tomography treatment-planning scans, which have to be taken in the exact treatment position of the patients, is essential for precision radiotherapy of breast cancer. Transverse tomography scans give all necessary informations for an optimal isodose distribution within the target volume for the individual patient, and maximal sparing of normal tissues (e.g. lung) is achieved. The exact topography of internal mammary nodes may also be incorporated in the planning scan with the help of lymphoscintigraphy. Conventional computerized tomography (CT) scanners have too small gantry openings (50-70 cm) to allow for proper positioning of the patients under treatment conditions. Using such treatment-planning scans for patients in the actual treatment position would cause an underdosage in excess of 5% within the target volume, when 60Co fields are used. Also, a much larger volume of normal tissues (mainly lung) would unnecessarily be irradiated. Treatment-planning scans obtained by TAT (transverse analog tomography) do not have the crucial positioning problems of conventional CT scanners and enable the precise transformation of a valid isodose distribution to each patient. In addition, positioning wedges (with adjustable wedge angles) may be placed under the patient to achieve the optimal treatment position. A useful alternative of TAT scanning for precise treatment planning of patients with breast cancer would be a CT scanner with a wide enough gantry opening to allow for any patient positioning under actual treatment conditions.

[Dosage load and value of cranial angiography. A digital intravenous/intra-arterial camera (105 mm) and imaging plates]

The integral dose and the dose to the organ at risk were calculated using the following angiographic techniques: 1. Intravenous DSA in the neck, 2. Intravenous DSA in the skull, 3. Intra-arterial DSA in the skull in searching for an aneurysm. This was compared with 4. 105 mm. camera technique and 5. An imaging plate technique. These methods have been compared with reference to dose and diagnostic value. Desirable developments for angiography in the future are discussed.

[Lumbosacral computed tomography and lumbosacral functional myelography. Dosimetric comparison and comparison of indications]

The integral dose and organ dose produced by spinal lumbosacral CT and lumbosacral functional myelography were compared, using a phantom. The value of these methods of investigation is discussed.

[Qualitative comparison of different irradiation technics]

A factor is defined which allows a quantitative comparison of different irradiation schemes. In this factor, the spatial as well as chronological dose distribution is taken into consideration, further it contains the varying radiosensitivity of the additionally exposed tissues. So the comparison of the radiobiologic effectiveness of different irradiation schemes based on this factor is more instructive than a simple comparison of the total dose. The study is continued by an analysis of the possible sources of error influencing the quality of a radiotherapy.

[Determination of the integral dose in computer tomography of the neurocranium]

The amount of exposure of the cranium is calculated on the basis of the measured dose distribution in craniocaudal direction and on the axial planes of the Alderson phantom. The integral dose of the cranium and the local dose at sensitive organs are used as a measure of radiation exposure.

[Energy dependence of the response of thermoluminescent dosimetry to high-energy electrons]

Sufficiently reproducible measuring results can be achieved even for simple TLD units by a control procedure which is easy to apply. It is demonstrated by means of the proposed control procedure that the dependence on energy of the TLD-100 rods is negligible in case of a measuring uncertainty of +/- 3%. This is confirmed by depth dose measurements in comparison with ionisation measurements and semiconductor measurements. TLD-100 rods are thus suitable for the measurement of the dose distribution in a typical solid phantom, such as the humanoid phantom of Alderson Research Laboratories, Long Island, N.Y. The results of these measurements, especially with regard to the verification of the irradiation planning, will be presented in a later report.

[Quantification of the biological effect of photons and electrons. 2. Probability of tumor destruction]

The study comprises two subjects: the probability of destruction of the irradiated tumor and the tumor immunogenicity and its changes in the course of radiotherapy. The distribution of Poisson was adopted in order to describe the tumor destruction. The probability of tumor destruction is analysed under consideration of the "critical cell number". The other part of the study deals with the immune system and its radiosensitivity. It is demonstrated that the patient's immune reaction can contribute to the tumor destruction if the irradiation planning is made in an adequate manner. Furthermore, different irradiation techniques are compared to one another. Pendulum therapy, especially with large fields, seems to be no superior method despite its geometric advantages.

[Quantification of the biologic effect of photons and electrons. I. Analysis of the injury factor in healthy tissue]

After having given a review of the NSD conception and the justification of its application, an injury factor based on NSD values is specified. This factor takes into consideration the dose distribution in time and space. In case of irradiation of a lung carcinoma for example, this factor is 49% for the spinal marrow. The injury factor can make possible a better comparison between different fractionation schemes and irradiation methods. Further tests and clinical measuring data are, however, still necessary.