Breakthrough SARS-CoV-2 infections in 620,000 U.S. Veterans, February 1, 2021 to August 13, 2021 (from www.medrxiv.org BMJ Yale).
Caution: Preprints are preliminary reports of work that have not been certified by peer review. They should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Given the scale, quality of work, and bona fides of the authors, it is likely their findings will be confirmed by peer review.
This study, by the Veteran’s Administration, which covers 2.7% of the U.S. population is impressive in its scale and promising in its capacity for follow up, shows rapid and significant waning of 3 vaccines' protection against infection. But then we've known for some time that the vaccines are not sterilizing.
It is not yet clear whether or not reductions in vaccine protection against infection will translate into similar reductions in protection against hospitalization, death, or prolonged post-viral morbidity. Let’s hope not. But we should definitely watch this space. Or better yet, the CDC should change its current policy and start watching it for us.
The numbers on reduced vaccine protection over time against infection:
Janssen: March, 92%---August, 3%
Moderna: March, 91%---August 64%
Pfizer: March, 95%---August, 50%
Abstract
National data on COVID-19 vaccine breakthrough infections is inadequate but urgently needed to determine U.S. policy during the emergence of the Delta variant. We address this gap by comparing SARS CoV-2 infection by vaccination status from February 1, 2021 to August 13, 2021 in the Veterans Health Administration, covering 2.7% of the U.S. population. Vaccine protection declined by mid-August 2021, decreasing from 91.9% in March to 53.9% (p<0.01, n=619,755). Declines were greatest for the Janssen vaccine followed by Pfizer–BioNTech and Moderna. Patterns of breakthrough infection over time were consistent by age, despite rolling vaccine eligibility, implicating the Delta variant as the primary determinant of infection. Findings support continued efforts to increase vaccination and an immediate, national return to additional layers of protection against infection. [Emphasis added]
Background
The messenger RNA vaccines BNT162b2 (Pfizer–BioNTech) and mRNA-1273 (Moderna) and the viral vector vaccine JNJ-78436735 (Janssen) have effectively prevented clinically significant disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) since their rollout in the U.S. in late 2020. Vaccines have also reduced the incidence of asymptomatic infection and associated infectivity (1). However, the U.S. has experienced a recent surge in cases of COVID-19, evident in July 2021 and dominated by the B.1.617.2 (Delta) variant (2). Although initial reports on vaccine effectiveness, including the six-month follow-up of the Pfizer-BioNTech trial (3), suggested sustained protection against infection and hospitalization (4-6), breakthrough infections have continued to emerge in vaccine recipients.
This phenomenon has been most comprehensively monitored in Israel, where breakthrough infections, hospitalizations, and deaths have occurred – despite high levels of vaccination in the population (7). As a result, Israel authorized boosters of the Pfizer-BioNTech vaccine for adults age ≥ 60 years in July 2021 and extended this authorization to adults age ≥ 50 years on August 13, 2021 (8). The U.S. subsequently announced their intention to offer boosters by late September, with the goal to stem the surge in SARS-CoV-2 infections caused by the Delta variant (9).
Availability of national data on breakthrough infections in the U.S. has been severely limited. The U.S. Centers for Disease Control and Prevention (CDC) transitioned in May 2021 from monitoring all reported vaccine breakthrough cases to focus on identifying and investigating only hospitalized or fatal cases due to any cause, including causes not related to COVID-19 (10). Here, we address this gap and examine infections by vaccination status in 619,755 Veterans during the period February 1, 2021 to August 13, 2021, encompassing the emergence and dominance of the Delta variant in the U.S. [Emphasis added]
The proportionate reduction in infection associated with vaccination declined for all vaccine types, with the largest declines for Janssen followed by Pfizer-BioNTech and Moderna (Figure 1).Specifically, in March, protection against infection was: 88% (95% CI, 87% to 89%) for Janssen; 92% (95% CI, 92% to 93%) for Moderna; and 91% (95% CI, 91% to 92%) for Pfizer-BioNTech. By August, protection against infection had declined to: 3% (95% CI, -7% to 12%) for Janssen; 64% (95% CI, 62%-66%) for Moderna; and 50% (95% CI, 47% to 52%) for Pfizer-BioNTech.
In related news:
Covid: Double vaccinated can still spread virus at home BBC
Covid: vaccinated as likely as unjabbed to infect cohabiters, study suggests The Guardian