Duration of COVID-19 mRNA Vaccine Effectiveness against Severe Disease

Abstract

Waning immunity following administration of mRNA-based COVID-19 vaccines remains a concern for many health systems. We undertook a study to determine if recent reports of waning for severe disease could have been attributed to design-related bias by conducting a study only among those detected with a first SARS-CoV-2 infection. We used a matched case-control study design with the study base being all individuals with first infection with SARS-CoV-2 reported in the State of Qatar between 1 January 2021 and 20 February 2022. Cases were those detected with first SARS-CoV-2 infection requiring intensive care (hard outcome), while controls were those detected with first SARS-CoV-2 infection who recovered without the need for intensive care. Cases and controls were matched in a 1:30 ratio for the calendar month of infection and the comorbidity category. Duration and magnitude of conditional vaccine effectiveness against requiring intensive care and the number needed to vaccinate (NNV) to prevent one more case of COVID-19 requiring intensive care was estimated for the mRNA (BNT162b2/mRNA-1273) vaccines. Conditional vaccine effectiveness against requiring intensive care was 59% (95% confidence interval (CI), 50 to 76) between the first and second dose, and strengthened to 89% (95% CI, 85 to 92) between the second dose and 4 months post the second dose in persons who received a primary course of the vaccine. There was no waning of vaccine effectiveness in the period from 4 to 6, 6 to 9, and 9 to 12 months after the second dose. This study demonstrates that, contrary to mainstream reports using hierarchical measures of effectiveness, conditional vaccine effectiveness against requiring intensive care remains robust till at least 12 months after the second dose of mRNA-based vaccines.

Number needed to vaccinate with a COVID-19 booster to prevent a COVID-19-associated hospitalization during SARS-CoV-2 Omicron BA.1 variant predominance, December 2021–February 2022, VISION Network: a retrospective cohort study

“…One study from Qatar examined NNV to prevent one COVID-19-associated intensive care unit admission between January 2021 and February 2022, finding an inverse relationship between NNV and age (178 at 60 years of age versus 1,183 at 30 years). 28 An international modeling study found a lower NNV to prevent one COVID-19-related death among surgery patients compared to the general population, with the lowest NNV among the oldest group (216 for elective cancer surgery patients ≥70 years during high SARS-CoV-2 incidence). 29 A study from Canada conducted using data from January 31 to February 6, 2021 found approximately half the NNV for patients with cardiovascular risk factors (obesity, diabetes, hypertension) compared to without, with NNV declining as age increased.…”

Number Needed to Vaccinate to prevent one death: a propensity score matching approach to COVID-19 vaccine evaluation in the center of Iran (short communication)

“…A matched case-control study in Qatar that investigated the NNV to prevent one case of COVID-19 requiring intensive care showed that 60-year-old individuals had a lower NNV compared to those aged 30 years old (15). The ndings of another prospective cohort study using international data revealed that 70year-old patients and older ones requiring cancer and non-cancer surgery had more desirable (i.e., lower) NNVs to prevent mortality than the general population.…”

Dynamics of Anti-S IgG Antibodies Titers after the Second Dose of COVID-19 Vaccines in the Manual and Craft Worker Population of Qatar

“…However, the high transmissibility of the virus [ 4 ] and the limitations of the surveillance yield an inaccurate estimation of the actual number of cases [ 5 ]. Furthermore, there are continuing reports of re-infection by circulating variants of SARS-CoV-2 which indicate that the acquired immunity wanes over time with respect to infection [ 6 ], though the protection against progression to severity remains robust [ 7 ] suggesting the latter is not solely a function of the antibody response.…”