scholarly journals Impact of the Second Epidemic Wave of SARS-CoV-2: Increased Exposure of Young People

2021 ◽  
Vol 9 ◽  
Author(s):  
Lisandru Capai ◽  
Shirley Masse ◽  
Toscane Fourié ◽  
Dorine Decarreaux ◽  
Jean Canarelli ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Herd Immunity ◽  
Wave Period ◽  
Quantitative Detection ◽  
Igg Antibodies ◽  
Cross Sectional ◽  
Clinical Laboratories ◽  
Serological Surveillance ◽  
Second Wave ◽  
Neutralization Antibody Titer

We aimed to use serological surveillance based on serial cross-sectional sampling of residual sera obtained from clinical laboratories to compare the differences in age and sex profiles of infected persons in the first and second waves of SARS-CoV-2 in Corsica, France. Residual sera were obtained, including samples from individuals of all ages collected for routine screening or clinical management by clinical laboratories. All the sera collected were tested for the presence of anti-SARS-CoV-2 IgG using a kit for semi-quantitative detection of IgG antibodies against the S1 domain of the viral spike protein (ELISA-S). Samples that were borderline and positive in ELISA-S were tested with an in-house virus neutralization test. During the second-wave period, we collected between 6 November, 2020 and 12 February, 2021, 4,505 sera from patients aged 0–101 years (60.4% women). The overall weighted seroprevalence of residual sera collected during the second-wave period [8.04% (7.87–9.61)] was significantly higher than the overall weighted seroprevalence estimated at the end of the first wave between 16 April and 15 June, 2020 [5.46% (4.37–7.00)] (p-value = 0.00025). Ninety-eight (30.1%) of the 326 samples tested in the VNT assay had a positive neutralization antibody titer. Estimated seroprevalence increased significantly for men [odds ratio (OR) OR = 1.80 (1.30–2.54); p-value = 0.00026] and for people under 30 years of age [OR = 2.17 (1.46–3.28); p-value = 0.000032]. This increase was observed in young adults aged 20–29 years among whom antibody frequencies were around four-fold higher than those observed at the end of the first wave. In conclusion, our seroprevalence estimates, including the proportion of the participants who had produced neutralizing antibodies, indicate that in February, 2021 the population of Corsica was still far from being protected against SARS-Cov-2 by “herd immunity.”

scholarly journals SARS-CoV-2 IgG Antibodies Seroprevalence and Sera Neutralizing Activity in MEXICO: A National Cross-Sectional Study during 2020

2021 ◽  
Vol 9 (4) ◽  
pp. 850
Author(s):  
José Esteban Muñoz-Medina ◽  
Concepción Grajales-Muñiz ◽  
Angel Gustavo Salas-Lais ◽  
Larissa Fernandes-Matano ◽  
Constantino López-Macías ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Neutralizing Antibodies ◽  
Herd Immunity ◽  
Cross Sectional Study ◽  
Molecular Techniques ◽  
Diagnostic Methods ◽  
Molecular Diagnostic ◽  
Enzyme Linked Immunosorbent Assay ◽  
Cross Sectional ◽  
Neutralizing Activity

Until recently, the incidence of COVID-19 was primarily estimated using molecular diagnostic methods. However, the number of cases is vastly underreported using these methods. Seroprevalence studies estimate cumulative infection incidences and allow monitoring of transmission dynamics, and the presence of neutralizing antibodies in the population. In February 2020, the Mexican Social Security Institute began conducting anonymous unrelated sampling of residual sera from specimens across the country, excluding patients with fever within the previous two weeks and/or patients with an acute respiratory infection. Sampling was carried out weekly and began 17 days before Mexico’s first officially confirmed case. The 24,273 sera obtained were analyzed by chemiluminescent-linked immunosorbent assay (CLIA) IgG S1/S2 and, later, positive cases using this technique were also analyzed to determine the rate of neutralization using the enzyme-linked immunosorbent assay (ELISA). We identified 40 CLIA IgG positive cases before the first official report of SARS-CoV-2 infection in Mexico. The national seroprevalence was 3.5% in February and 33.5% in December. Neutralizing activity among IgG positives patients during overall study period was 86.1%. The extent of the SARS-CoV-2 infection in Mexico is 21 times higher than that reported by molecular techniques. Although the general population is still far from achieving herd immunity, epidemiological indicators should be re-estimated based on serological studies of this type.

scholarly journals High Community SARS-CoV-2 Antibody Seroprevalence in a Ski Resort Community, Blaine County, Idaho, US. Preliminary Results

2020 ◽  
Author(s):  
Colleen McLaughlin ◽  
Margaret K. Doll ◽  
Kathryn T Morrison ◽  
William L McLaughlin ◽  
Terry OConnor ◽  
...  
Keyword(s):  
Disease Surveillance ◽  
Population Distribution ◽  
A Priori ◽  
Herd Immunity ◽  
Sensitivity Analyses ◽  
Igg Antibodies ◽  
Cross Sectional ◽  
Diagnostic Uncertainty ◽  
Ski Resort ◽  
Zip Code

Community-level seroprevalence surveys are needed to determine the proportion of the population with previous SARS-CoV-2 infection, a necessary component of COVID-19 disease surveillance. In May, 2020, we conducted a cross-sectional seroprevalence study of IgG antibodies for nucleocapsid of SARS-CoV-2 among the residents of Blaine County, Idaho, a ski resort community with high COVID-19 attack rates in late March and Early April (2.9% for ages 18 and older). Participants were selected from volunteers who registered via a secure web link, using prestratification weighting to the population distribution by age and gender within each ZIP Code. Participants completed a survey reporting their demographics and symptoms; 88% of volunteers who were invited to participate completed data collection survey and had 10 ml of blood drawn. Serology was completed via the Abbott Architect SARS-CoV-2 IgG immunoassay. Primary analyses estimated seroprevalence and 95% credible intervals (CI) using a hierarchical Bayesian framework to account for diagnostic uncertainty. Stratified models were run by age, sex, ZIP Code, ethnicity, employment status, and a priori participant-reported COVID-19 status. Sensitivity analyses to estimate seroprevalence included base models with post-stratification for ethnicity, age, and sex, with or without adjustment for multi-participant households. IgG antibodies to the virus that causes COVID-19 were found among 22.7% (95% CI: 20.1%, 25.5%) of residents of Blaine County. Higher levels of antibodies were found among residents of the City of Ketchum 34.8% (95% CI 29.3%, 40.5%), compared to Hailey 16.8% (95%CI 13.7%, 20.3%) and Sun Valley 19.4% (95% 11.8%, 28.4%). People who self-identified as not believing they had COVID-19 had the lowest prevalence 4.8% (95% CI 2.3%, 8.2%). The range of seroprevalence after correction for potential selection bias was 21.9% to 24.2%. This study suggests more than 80% of SARS-CoV-2 infections were not reported. Although Blaine County had high levels of SARS-CoV-2 infection, the community is not yet near the herd immunity threshold.

scholarly journals Prevalence and associated characteristics of anti-SARS-CoV-2 antibodies in Mexico 5 months after pandemic arrival

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Cristina Díaz-Salazar ◽  
Adriana Sánchez-García ◽  
René Rodríguez-Gutiérrez ◽  
Adrián Camacho-Ortiz ◽  
Donato Saldívar-Rodríguez ◽  
...  
Keyword(s):  
Clinical Characteristics ◽  
Statistical Significance ◽  
Herd Immunity ◽  
Epidemiological Data ◽  
City Government ◽  
Epidemiological Surveillance ◽  
Continuous Variables ◽  
Igg Antibodies ◽  
Government Employees ◽  
Cross Sectional

Abstract Background Seroprevalence of anti-SARS-CoV-2 antibodies is now available in several world regions to better estimate transmission dynamics. However, to date, there is no epidemiological data regarding anti-SARS-CoV-2 prevalence in Mexico. Therefore, we aimed to determine the prevalence of anti-SARS-CoV-2 antibodies and define the clinical and demographic characteristics associated with seroprevalence. Methods We conducted a cross-sectional serological survey in Ciudad Guadalupe, NL, Mexico. City government employees voluntarily participated during July 2020. Demographic and clinical characteristics were collected at the time of blood sampling to analyze the associated characteristics. IgM/IgG antibodies were determined using a qualitative chemiluminescent immunoassay. Descriptive statistics were used for categorical and continuous variables. Statistical significance was tested using the Chi-squared test, Student’s t-test and the Mann–Whitney. Logistic regression models and the odds ratios (adjusted and unadjusted) were used to estimate the association of demographic and clinical characteristics. Results Of the 3,268 participants included, 193 (5.9%, 95% CI 5.1–6.8) tested positive for IgM/IgG against SARS-CoV-2. Sex, city of residence, and comorbidities did not show any association with having IgM/IgG antibodies. A total of 114 out of 193 (59.1%) subjects with a positive test were asymptomatic, and the odds of being positive were higher in those who reported symptoms of COVID-19 in the previous four weeks to the survey (OR 4.1, 95% CI 2.9–5.5). Conclusions There is a low rate of SARS-CoV-2 infection among government employees that have continuously been working during the pandemic. Six in ten infections were asymptomatic, and seroprevalence is low and still far from herd immunity. Epidemiological surveillance and preventive measures should be mandatory.

scholarly journals Seroprevalence of IgG antibodies against SARS coronavirus 2 in Belgium – a prospective cross-sectional study of residual samples

2020 ◽  
Author(s):  
Herzog Sereina ◽  
De Bie Jessie ◽  
Abrams Steven ◽  
Wouters Ine ◽  
Ekinci Esra ◽  
...  
Keyword(s):  
Herd Immunity ◽  
World Health Organisation ◽  
Added Value ◽  
World Health ◽  
Igg Antibodies ◽  
Cross Sectional ◽  
Horizon 2020 ◽  
Age Related ◽  
The World ◽  
Belgian Population

AbstractBackgroundIn the first weeks of the COVID-19 epidemic in Belgium, a repetitive national serum collection was set up to monitor age-related exposure through emerging SARS-CoV-2 antibodies. First objective was to estimate the baseline seroprevalence and seroincidence using serial survey data that covered the start of a national lock-down period installed soon after the epidemic was recognized.MethodsA prospective serial cross-sectional seroprevalence study, stratified by age, sex and region, started with two collections in April 2020. In residual sera taken outside hospitals and collected by diagnostic laboratories, IgG antibodies against S1 proteins of SARS-CoV-2 were measured with a semi-quantitative commercial ELISA. Seropositivity (cumulative, by age category and sex) and seroincidence over a 3 weeks period were estimated for the Belgian population.FindingsIn the first collection, IgG antibodies were detected in 100 out of 3910 samples, whereas in the second collection 193 out of 3391 samples were IgG positive. The weighted overall seroprevalence increased from 2·9% (95% CI 2·3 to 3·6) to 6·0% (95% CI 5·1 to 7·1), reflected in a seroincidence estimate of 3·1% (95% CI 1·9 to 4·3). Age-specific seroprevalence significantly increased in the age categories 20-30, 80-90 and ≥90. No significant sex effect was observed.InterpretationDuring the start of epidemic mitigation by lockdown, a small but increasing fraction of the Belgian population showed serologically detectable signs of exposure to SARS-CoV-2.FundingThis independent researcher-initiated study acknowledges financial support from the Antwerp University Fund, the Flemish Research Fund, and European Horizon 2020.Research in contextEvidence before this studyThis is the first study reporting seroprevalence and seroincidence of IgG against SARS-CoV-2 in the Belgian population. Worldwide, PCR tests are being performed to identify mainly sick people suffering from COVID-19. However, seroprevalence studies are important and feasible to study the proportion of the population that has already been in contact with the virus, which helps to understand the likelihood of asymptomatic infections or infections with mild symptoms.From 11 March to 11 May, updates on the COVID-19 pandemic by the World Health Organisation as well as bulletins from the Belgian Scientific Institute for Public Health, Sciensano, were consulted daily. Press releases from all over the world were monitored during that period. Google, PubMed as well as the pre-print server medrxiv were consulted by searching the terms “seroprevalence SARS-CoV-2” and “COVID-19”,Added value of this studyThis study reports that seroprevalence increased in Belgium from 2·9% (95% CI 2·3 to 3·6) to 6·0% (95% CI 5·1 to 7·1) over a period of 3 weeks during lockdown (30 March-5 April 2020 & 20-26 April 2020) with seroincidence estimate of 3·1% (95% CI 1·9 to 4·3). Moreover, a significant increase in seroprevalence in the age categories 20-30 and ≥80 and within each sex were reported.Implications of all the available evidenceSeroprevalences worldwide indicate that an increasing fraction of the population has already been exposed to SARS-CoV-2. The continuous monitoring of seroprevalences is valuable to calibrate the response to the epidemic and to guide policy makers to control the epidemic wave and potential future waves and to avoid a deconfinement strategy leading to a rebound. However, it seems likely that natural exposure during this pandemic might not soon deliver the required level of herd immunity and there will be a substantial need for mass vaccination programmes to save time and lives.

scholarly journals Serological Screening for Antibodies against SARS-CoV-2 in Dutch Shelter Cats

Viruses ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1634
Author(s):  
W. J. R. van der Leij ◽  
Els M. Broens ◽  
Jan Willem Hesselink ◽  
Nancy Schuurman ◽  
Johannes C. M. Vernooij ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Large Scale ◽  
Companion Animals ◽  
Significant Risk ◽  
Cross Sectional Study ◽  
Serum Samples ◽  
Serological Screening ◽  
Cross Sectional ◽  
Animal Shelters ◽  
Second Wave

The COVID-19 pandemic raised concerns that companion animals might be infected with, and could become a reservoir of, SARS-CoV-2. As cats are popular pets and susceptible to Coronavirus, we investigated the seroprevalence of SARS-CoV-2 antibodies in shelter cats housed in Dutch animal shelters during the COVID-19 pandemic. In this large-scale cross-sectional study, serum samples of shelter cats were collected during the second wave of human COVID-19 infections in The Netherlands. Seroprevalence was determined by using an indirect protein-based ELISA validated for cats, and a Virus Neutralization Test (VNT) as confirmation. To screen for feline SARS-CoV-2 shedding, oropharyngeal and rectal swabs of cats positive for ELISA and/or VNT were analyzed using PCR tests. In 28 Dutch animal shelters, 240 shelter cats were convenience sampled. Two of these cats (0.8%; CI 95%: 0.1–3.0%) were seropositive, as evidenced by the presence of SARS-CoV-2 neutralizing antibodies. The seropositive animals tested PCR negative for SARS-CoV-2. Based on the results of this study, it is unlikely that shelter cats could be a reservoir of SARS-CoV-2 or pose a (significant) risk to public health.

scholarly journals Prevalence of SARS-CoV-2 antibodies in France: results from nationwide serological surveillance

2020 ◽  
Author(s):  
Stéphane Le Vu ◽  
Gabrielle Jones ◽  
François Anna ◽  
Thierry Rose ◽  
Jean-Baptiste Richard ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
School Age Children ◽  
French Population ◽  
Public Health Response ◽  
Neutralising Antibodies ◽  
Cross Sectional ◽  
Serological Surveillance ◽  
Epidemic Wave

AbstractBackgroundAssessment of cumulative incidence of SARS-CoV-2 infections is critical for monitoring the course and the extent of the epidemic. As asymptomatic or mild cases were typically not captured by surveillance data in France, we implemented nationwide serological surveillance. We present estimates for prevalence of anti-SARS-CoV-2 antibodies in the French population and the proportion of infected individuals who developed potentially protective neutralizing antibodies throughout the first epidemic wave.MethodsWe performed serial cross-sectional sampling of residual sera over three periods: prior to (9-15 March), during (6-12 April) and following (11-17 May) a nationwide lockdown. Each sample was tested for anti-SARS-CoV-2 IgG antibodies targeting the Nucleoprotein and Spike using two Luciferase-Linked ImmunoSorbent Assays, and for neutralising antibodies using a pseudo-neutralisation assay. We fitted a general linear mixed model of seropositivity in a Bayesian framework to derive prevalence estimates stratified by age, sex and region.FindingsIn total, sera from 11 021 individuals were analysed. Nationwide seroprevalence of SARS-CoV-2 antibodies was estimated at 0.41% [0.05−0.88] mid-March, 4.14% [3.31−4.99] mid-April and 4.93% [4.02−5.89] mid-May. Approximately 70% of seropositive individuals had detectable neutralising antibodies. Seroprevalence was higher in regions where circulation occurred earlier and was more intense. Seroprevalence was lowest in children under 10 years of age (2.72% [1.10−4.87]).InterpretationSeroprevalence estimates confirm that the nationwide lockdown substantially curbed transmission and that the vast majority of the French population remains susceptible to SARS-CoV-2. Low seroprevalence in school age children suggests limited susceptibility and/or transmissibility in this age group. Our results show a clear picture of the progression of the first epidemic wave and provide a framework to inform the ongoing public health response as viral transmission is picking up again in France and globally.FundingSanté publique France.

scholarly journals Herd immunity to SARS-CoV-2 in the Novosibirsk Region population amid the COVID-19 pandemic

2021 ◽  
Vol 66 (4) ◽  
pp. 299-309
Author(s):  
A. Yu. Popova ◽  
V. S. Smirnov ◽  
E. B. Ezhlova ◽  
A. A. Mel’nikova ◽  
L. V. Samoilova ◽  
...  
Keyword(s):  
Nucleocapsid Protein ◽  
Herd Immunity ◽  
Threshold Level ◽  
Igg Antibodies ◽  
Pasteur Institute ◽  
Microsoft Excel ◽  
Cross Sectional ◽  
Novosibirsk Region ◽  
Stage 1 ◽  
The Unemployed

Aim. To determine the level of SARS-CoV-2 seroprevalence among the Novosibirsk Region population against the background of the COVID-19 pandemic.Material and methods. The work was carried out in 2 phases: 1) a cross-sectional cohort study performed 28.06– 15.07.2020; 2) longitudinal cohort 3-stage seromonitoring: 1st stage 28.06–15.07.2020; 2nd 14.09–04.10.2020; 3rd 10–30.12.2020 The work was carried out according to a unified methodology developed by Rospotrebnadzor with the participation of St-Petersburg Pasteur Institute, taking into account the recommendations of the WHO. IgG antibodies to the SARS-CoV-2 nucleocapsid protein were detected by ELISA using a kit of reagents produced by the SRCMSB (Obolensk) according to the manufacturer’s instructions. Statistical analysis was performed using Microsoft Excel 2010 and other programs.Results. The seroprevalence in the region’s population was 9.1% (95% CI 8.0–10.2): maximum in children 14–17 years old (17.6%, 95% CI 12.3–23.9) and persons over 75 years (14.8%, 95% CI 11.4–18.8), minimum among persons 30–39 years old (4.9%, 95% CI 3.0–8.0). Increased rate was noted among the unemployed (15.4%, 95% CI 9.9–17.1) and other individuals (13.0%, 95% CI 8.6–18.5). Seroprevalence was 33.3% (95% CI 16.3–59.0) in COVID-19 convalescents and 19.0% (95% CI 13.9-25.0) in contact persons. More than 94.7% (95% CI 91.2–97.2) of seropositive individuals were asymptomatic. During the serological monitoring, seroprevalence increased from 7.4% (95% CI 6.2–8.9) at 1st stage 1 to 12.4% (95% CI 10.6–14.3) at 2nd , and 31% (95% CI 28.8–33.3) at 3rd stage.Conclusion. SARS-CoV-2 herd immunity has not reached the threshold level, this does not exclude exacerbation of the epidemic process.

SARS-CoV-2 Biology Insights, Part IV.Antibody-Dependent Enhancement (ADE) and the tricky “Herd Immunity”: narrative review (Preprint)

2020 ◽  
Author(s):  
Laura Lafon-Hughes
Keyword(s):  
Viral Infection ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Whooping Cough ◽  
Common Knowledge ◽  
Herd Immunity ◽  
Life Quality ◽  
Host Cells ◽  
System P

BACKGROUND It is common knowledge that vaccination has improved our life quality and expectancy since it succeeded in achieving almost eradication of several diseases including chickenpox (varicella), diphtheria, hepatitis A and B, measles, meningococcal, mumps, pneumococcal, polio, rotavirus, rubella, tetanus and whooping cough (pertussis) Vaccination success is based on vaccine induction of neutralizing antibodies that help fight the infection (e.g. by a virus), preventing the disease. Conversely, Antibody-dependent enhancement (ADE) of a viral infection occurs when anti-viral antibodies facilitate viral entry into host cells and enhance viral infection in these cells. ADE has been previously studied in Dengue and HIV viruses and explains why a second infection with Dengue can be lethal. As already reviewed in Part I and Part II, SARS-Cov-2 shares with HIV not only 4 sequences in the Spike protein but also the capacity to attack the immune system. OBJECTIVE As HIV presents ADE, we wondered whether this was also the case regarding SARS-CoV-2. METHODS A literature review was done through Google. RESULTS SARS-CoV-2 presents ADE. As SARS, which does not have the 4 HIV-like inserts, has the same property, ADE would not be driven by the HIV-like spike sequences. CONCLUSIONS ADE can explain the failure of herd immunity-based strategies and will also probably hamper anti-SARS-CoV-2 vaccine development. As reviewed in Part I, there fortunately are promising therapeutic strategies for COVID-19, which should be further developed. In the meantime, complementary countermeasures to protect mainly the youth from this infection are presented to be discussed in Part V Viewpoint.

scholarly journals Changes in Cytomegalovirus Seroprevalence Among U.S. Children Aged 1–5 Years: The National Health and Nutrition Examination Surveys

2020 ◽  
Author(s):  
Molly R Petersen ◽  
Eshan U Patel ◽  
Alison G Abraham ◽  
Thomas C Quinn ◽  
Aaron A R Tobian
Keyword(s):  
Confidence Interval ◽  
National Health ◽  
Immunoglobulin G ◽  
Igg Antibodies ◽  
Cross Sectional ◽  
Health And Nutrition ◽  
Prevalence Difference ◽  
The Cross ◽  
Us Children

Abstract Data from the cross-sectional National Health and Nutrition Examination Surveys (NHANES) indicate that the seroprevalence of cytomegalovirus immunoglobulin G (IgG) antibodies among US children aged 1–5 years was 20.7% (95% confidence interval [CI]: 14.0, 29.0) in 2011–2012 and 28.2% (95% CI: 23.1–34.0) in 2017–2018 (adjusted prevalence difference, +7.6% [95% CI: −.4, +15.6]).

scholarly journals COVID-19 Vaccine Intention among Healthcare Workers in Saudi Arabia: A Cross-Sectional Survey

Vaccines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 835
Author(s):  
Mohammed Noushad ◽  
Mohammad Zakaria Nassani ◽  
Anas B. Alsalhani ◽  
Pradeep Koppolu ◽  
Fayez Hussain Niazi ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Healthcare System ◽  
Healthcare Workers ◽  
Vaccine Coverage ◽  
Vaccination Campaign ◽  
Herd Immunity ◽  
Positive Sign ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Public Health Strategies

The COVID-19 pandemic has caused largescale morbidity and mortality and a tremendous burden on the healthcare system. Healthcare workers (HCWs) require adequate protection to avoid onward transmission and minimize burden on the healthcare system. Moreover, HCWs can also influence the general public into accepting the COVID-19 vaccine. Therefore, determining COVID-19 vaccine intention among HCWs is of paramount importance to plan tailor-made public health strategies to maximize vaccine coverage. A structured questionnaire was administered in February and March 2021 among HCWs in Saudi Arabia using convenience sampling, proceeding the launch of the vaccination campaign. HCWs from all administrative regions of Saudi Arabia were included in the study. In total, 674 out of 1124 HCWs responded and completed the survey (response rate 59.9%). About 65 percent of the HCWs intended to get vaccinated. The intention to vaccinate was significantly higher among HCWs 50 years of age or older, Saudi nationals and those who followed the updates about COVID-19 vaccines (p < 0.05). The high percentage (26 percent) of those who were undecided in getting vaccinated is a positive sign. As the vaccination campaign gathers pace, the attitude is expected to change over time. Emphasis should be on planning healthcare strategies to convince the undecided HCWs into accepting the vaccine in order to achieve the coverage required to achieve herd immunity.

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