Key points How effective is COVID-19 vaccination after recovery from previous SARS-CoV-2 infection? Findings In this cohort study of more than 95,000 Rhode Island residents from March 2020 to December 2021, including residents and employees of long-term congregate care facilities (LTCC), completion of the primary vaccination series after Recovery from COVID-19 was associated with 49% protection against reinfection among LTCC residents, 47% protection among LTCC employees, and 62% protection in the general population during periods when SARS strains predominated. CoV-2 wild type, alpha and delta. Meaning These findings suggest that among people who recovered from COVID-19, subsequent completion of the primary vaccination series reduced the risk of reinfection by approximately half . |
Current evidence suggests that people who experience SARS-CoV-2 infection are susceptible to reinfection . While evidence suggests that hospitalization and death rates are substantially lower in people who have been reinfected, the dynamics of SARS-CoV-2 reinfection are still not well understood. Previous SARS-CoV-2 infection confers some immunity to unvaccinated people, but this natural immunity wanes over time. Additionally, the JNJ-78436735 (Janssen), mRNA-1273 (Moderna), and BNT162b2 (Pfizer-BioNTech) vaccines have been shown to offer substantial protection against COVID-19 infection and remain effective against newer variants.
Our primary objective was to quantify the effectiveness associated with vaccination against reinfection among people who had previously been infected with SARS-CoV-2 before vaccination. Secondary objectives were to estimate the probability of reinfection at 3, 6, and 9 months after recovery from the primary infection and to evaluate the associations of measurable risk factors with reinfection. Our analysis has particular relevance to the ongoing discussion about vaccination requirements for people who have recovered from COVID-19.
Summary
Importance
The benefit of vaccination in preventing reinfection among people who have previously been infected with SARS-CoV-2 is largely unknown.
Aim
Obtain population-based estimates of the probability of SARS-CoV-2 reinfection and the effectiveness associated with vaccination after recovery from COVID-19.
Design, environment and participants
This cohort study used Rhode Island statewide surveillance data from March 1, 2020 to December 9, 2021 on COVID-19 vaccinations, laboratory-confirmed cases, hospitalizations, and deaths to conduct a retrospective study. population-based during periods when wild-type, alpha, and delta strains of SARS-CoV-2 predominated.
Participants included Rhode Island residents aged 12 years and older who had been previously diagnosed with COVID-19 and were unvaccinated at the time of first infection, stratified into 3 subpopulations: long-term congregate care (LTCC) residents, employees of LTCC and the general population (i.e., individuals not associated with congregate settings). Data was analyzed from October 2021 to January 2022.
Exhibitions
Completion of the primary vaccination series, defined as 14 days after the second dose of an mRNA vaccine or 1 dose of vector virus vaccine.
Main results and measures
The primary outcome was SARS-CoV-2 reinfection, defined as a laboratory-confirmed positive result in a polymerase chain reaction (PCR) or antigen test at least 90 days after the first laboratory-confirmed positive result in a PCR or antigen test.
Results
Overall, 3,124 LTCC residents (median age [IQR], 81 [71-89]; 1,675 [53.6%] female), 2,877 LTCC employees (median age [IQR], 41 [30-53]; 2,186 [76.0%] women), and 94,516 members of the general population (median [IQR] age, 35 [24-52] years; 45,030 [47.6%] women) met eligibility criteria.
The 9-month probability of reinfection for those not vaccinated after recovery from previous COVID-19 was 13.0% (95% CI, 12.0%-14.0%) among LTCC residents , 10.0% (95% CI, 8.8%-11.5%) among LTCC employees and 1.9% (95% CI, 1.8%-2.0%) among the general population .
Completion of the primary vaccination series after infection was associated with 49% protection (95% CI, 27%-65%) among LTCC residents, 47% protection (95% CI, 19%- 65%) among LTCC employees and 62% (95% CI, 56%-68%) protection in the general population against reinfection.
CPVS indicates completion of the primary vaccination series; LTCC, long-term group care.
Conclusions and relevance
"Vaccination after recovery from COVID-19 was associated with substantial benefit, reducing the risk of reinfection by approximately half."
These findings suggest that the risk of SARS-CoV-2 reinfection after recovery from COVID-19 was relatively high among unvaccinated people. Vaccination after recovery from COVID-19 was associated with reducing the risk of reinfection by about half.
Discussion
This cohort study is one of the first, to our knowledge, to examine the effectiveness of vaccination among people who recovered from COVID-19 and were not vaccinated at the time of their first infection; that is, we examined the effectiveness associated with vaccination after a primary infection.
This analysis provides important information for the development of the guidance, particularly regarding residents of long-term congregate care facilities (LTCC) facilities and employees who work in these settings. Previous infection is now taken into account in the development of U.S. Centers for Disease Control and Prevention guidelines and has been used as an argument against vaccination requirements.
Conclusions
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