Reduced Odds of SARS-CoV-2 Reinfection after Vaccination among New York City Adults, June–August 2021

Abstract

BackgroundBelief in immunity from prior infection and concern that vaccines might not protect against new variants are contributors to vaccine hesitancy. We assessed effectiveness of full and partial COVID-19 vaccination against reinfection when Delta was the predominant variant in New York City.MethodsWe conducted a case-control study in which case-patients with reinfection during June 15– August 31, 2021 and control subjects with no reinfection were matched (1:3) on age, sex, timing of initial positive test in 2020, and neighborhood poverty level. Conditional logistic regression was used to calculate matched odds ratios (mOR) and 95% confidence intervals (CI).ResultsOf 349,598 adult residents who tested positive for SARS-CoV-2 infection in 2020, did not test positive again >90 days after initial positive test through June 15, 2021, and did not die before June 15, 2021, 1,067 were reinfected during June 15–August 31, 2021. Of 1,048 with complete matching criteria data, 499 (47.6%) were known to be symptomatic for COVID-19-like-illness, and 75 (7.2%) were hospitalized. Unvaccinated individuals, compared with fully vaccinated individuals, had elevated odds of reinfection (mOR, 2.23; 95% CI, 1.90, 2.61), of symptomatic reinfection (mOR, 2.17; 95% CI, 1.72, 2.74), and of reinfection with hospitalization (mOR, 2.59; 95% CI, 1.43, 4.69). Partially versus fully vaccinated individuals had 1.58 (95% CI: 1.22, 2.06) times the odds of reinfection. All three vaccines authorized or approved for use in the U.S. were similarly effective.ConclusionAmong adults with previous SARS-CoV-2 infection, vaccination reduced odds of reinfections when the Delta variant predominated.

Effectiveness of CoronaVac, ChAdOx1 nCoV-19, BNT162b2, and Ad26.COV2.S among individuals with previous SARS-CoV-2 infection in Brazil: a test-negative, case-control study

“…11 Emerging evidence suggests that vaccination with ChAdOx1 nCoV-19 (AstraZeneca), Ad26.COV2.S (Janssen), BNT162b2 (tozinameran; Pfizer-BioNtech), or mRNA-1273 (elasomeran; Moderna) confers additional protection against symptomatic reinfection among individuals with previous SARS-CoV-2 infection. [12][13][14][15][16][17][18] However, only one study has assessed protection against severe outcomes in previously infected individuals, with just 75 hospital admissions and two deaths. 18 Moreover, data for inactivated vaccines, which account for almost half of all doses given globally, are still needed.…”

“…[12][13][14][15][16][17][18] However, only one study has assessed protection against severe outcomes in previously infected individuals, with just 75 hospital admissions and two deaths. 18 Moreover, data for inactivated vaccines, which account for almost half of all doses given globally, are still needed. 19 Brazil has recorded more than 22 million SARS-CoV-2 infections and 600 000 deaths as of Nov 15, 2021.…”

Effectiveness of CoronaVac, ChAdOx1, BNT162b2 and Ad26.COV2.S among individuals with prior SARS-CoV-2 infection in Brazil

“…20 To our knowledge, only one prior study reported vaccine effectiveness among previously infected individuals against COVID-19 related hospitalization or death; with just 75 outcomes and three vaccines evaluated, power in that study was limited for assessing vaccine and dose-specific effectiveness, but estimates ranged from 58% (BNT162b2) to 68% (mRNA-1273), with no significant protection from Ad26.COV2.S. 19 We found that protection against these severe outcomes, from 14 days after the second dose, was greater than 80% for the three two-dose vaccines (CoronaVac, ChAdOx1, and BNT162b2). These results are consistent with recent data showing that previously infected individuals have even greater increases in T-cell and B-cell responses following vaccination compared with those without prior infection.…”

“…12 Emerging evidence suggests that vaccination with ChAdOx1, Ad26.COV2.S, BNT162b2, or mRNA-1273 does confer additional protection against symptomatic reinfection among individuals with prior SARS-CoV-2 infection. [13][14][15][16][17][18][19] However, only one study has assessed protection against severe outcomes, with just 75 hospitalizations and 2 deaths. 19 Moreover, data for inactivated vaccines, which account for almost half of all doses given globally, are lacking.…”

“…[13][14][15][16][17][18][19] However, only one study has assessed protection against severe outcomes, with just 75 hospitalizations and 2 deaths. 19 Moreover, data for inactivated vaccines, which account for almost half of all doses given globally, are lacking. 20 Brazil has recorded more than 22 million COVID-19 infections and 600,000 deaths to date.…”