Prior SARS-CoV-2 an infection and danger of breakthrough an infection following mRNA vaccination

“Are individuals vaccinated after SARS-CoV-2 an infection higher protected in opposition to breakthrough an infection than these vaccinated with out prior an infection?”

With this query in thoughts, the workforce of researchers from Qatar undertook a big retrospective cohort research on 1,531,736 people vaccinated in opposition to extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with both BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) vaccine between December 21, 2020, and September 19, 2021.

The research, just lately printed in The Journal of the American Medical Affiliation, deduced that earlier SARS-CoV-2 an infection is related to a statistically important diminished hazard of breakthrough an infection amongst recipients of each the BNT162b2 (Pfizer-BioNTech) and the mRNA-1273 (Moderna) vaccines.

Study: Association of Prior SARS-CoV-2 Infection With Risk of Breakthrough Infection Following mRNA Vaccination in Qatar. Image Credit: NIAID

SARS-CoV-2 an infection and immunization standing in Qatar

Coronavirus illness 19 (COVID-19) vaccination drive started in December 2020 in Qatar, initially with the BNT162b2 (Pfizer-BioNTech) vaccine and, three months later, including the mRNA-1273 (Moderna) vaccine. Later from January by way of June 2021, the nation skilled two SARS-CoV-2 waves, dominated by the Alpha (B.1.1.7) and Beta (B.1.351) variants.

By the summer time of 2021, Delta had grow to be the dominant variant. The workforce took a chance by way of the entire situation to evaluate whether or not individuals vaccinated with a previous SARS-CoV-2 an infection had a decrease incidence of breakthrough infections than these vaccinated with out earlier an infection.

Research design

Affiliation between prior an infection and acquisition of an infection after vaccination was investigated utilizing two retrospectively matched-cohort research. The research leveraged the nationwide, federated databases that captured all SARS-CoV-2–associated information, together with an infection, immunization, and demographic particulars of pertinent people for the reason that begin of the epidemic. The eligible research inhabitants included a complete of 1,531,736 eligible BNT162b2-vaccinated and mRNA-1273–vaccinated people within the federated database between December 21, 2020, and September 19, 2021.

The incidence of documented SARS-CoV-2 an infection after the second vaccine dose was in contrast within the cohort of people who skilled PCR-confirmed an infection earlier than vaccination vs. incidence amongst these with no document of a previous an infection for each the vaccine cohorts. The follow-up lasted from 14 days after the second dose as much as the earliest prevalence of both PCR-positive nasopharyngeal swab, all-cause dying, or end-of-study censoring (September 19, 2021).

To regulate for any variations in publicity danger and variant publicity, people have been precise matched based mostly on prior an infection standing in a 1:1 ratio by intercourse, 5-year age group, nationality, and calendar week of first vaccine dose. Cumulative incidence of an infection was calculated utilizing the Kaplan-Meier estimator methodology.

A further evaluation was carried out to evaluate the affiliation between the timing of boosting pure immunity by way of vaccination and the incidence of breakthrough an infection.

Research findings

The BNT162b2-vaccinated cohort comprised 99,226 people with prior an infection (PCR-positive nasopharyngeal swab) and 290,432 matched people with out prior an infection. Amongst these, 159 reinfections occurred in these with and 2509 in these with out prior an infection, 14 days or extra after the second dose.

Cumulative an infection incidence amongst BNT162b2-vaccinated people was an estimated 0.15% (95percentCI, 0.12%-0.18%) in these with and 0.83% (95percentCI, 0.79%-0.87%) in these with out prior an infection at 120 days of follow-up. Cumulative an infection incidence appeared to speed up amongst these with out prior an infection after the 110th day of follow-up.

Within the case of mRNA-1273-vaccinated, 58,096 people with and 169,514 matched people with out prior PCR-confirmed an infection comprised the cohort. Forty-three and 368 reinfections occurred in vaccinated people with and with out prior an infection, respectively. It interpreted right into a cumulative an infection incidence of an estimated 0.11% (95percentCI, 0.08%-0.15%) in these with and 0.35% (95percentCI, 0.32%-0.40%) in these with out prior an infection at 120 days of follow-up. Right here, in mRNA-1273-vaccinated people, cumulative an infection incidence appeared to speed up amongst vaccinated people with out prior an infection after the 80th day of follow-up.

The research additionally discovered that vaccinated people who had a previous SARS-CoV-2 an infection 6 months or extra earlier than dose 1 have been at considerably decrease danger for breakthrough an infection than those that obtained contaminated lower than 6 months earlier than the primary dose.


Given the utilization of a giant dataset, the research establishes its reliability for implications over a wider inhabitants throughout the globe.

“Prior an infection amongst these vaccinated—a hybrid of pure and vaccine immunity—gave the impression to be related to extra discount in breakthrough an infection,” the workforce concludes.

Incidence of breakthrough an infection accelerates with time after the second dose amongst these with no prior an infection, suggesting waning of vaccine-induced immunity over time.

Proof means that the mRNA-1273 vaccine protects higher than the BNT162b2. Nonetheless, the workforce speculates that the noticed variations in breakthrough an infection incidence in vaccinated people may very well be attributable to – a further one-week interval between two doses of mRNA-1273 (an extended dose interval may be related to an improved immunity) and a bigger vaccine dose of mRNA-1273.

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