Vaccines: 53-84% vs Delta infection, 85-96% vs hospitalization
Do Delta ‘breakthroughs’ really mean vaccine protection is waning, and are boosters the answer?
[Science News report.] “[Vaccine] efficacy drops with Delta. That is indisputable,” says Leif Erik Sander, an infectious disease expert at the Charité University Hospital in Berlin. But exactly how much it drops differs across studies. In a report this week analyzing weekly reports on nursing home residents across the United States, researchers found that the messenger RNA (mRNA) vaccines made by Pfizer and Moderna had an efficacy against all infections that went from 75% pre-Delta to 53% after it took over. (The variant accounts for more than 90% of U.S. cases now.). “Protection against hospitalization looks quite stable,” Sander says. In the New York study, for example, vaccine efficacy against hospitalization for COVID-19 stayed close to 95%. Data from the Israeli Ministry of Health suggests protection against severe disease is still nearly 92% for people 50 and younger and 85% for those older than 50. Public Health England estimates that two doses of vaccine provide 96% protection against hospitalization.
County-Level Vaccination Coverage and Rates of COVID-19 Cases and Deaths in the United States
[Preprint.] We evaluated the association between county-level COVID-19 vaccine uptake and rates of COVID-19 cases and deaths in the United States from April 1, 2021 through July 31, 2021 controlling for a broad set of county-level environmental, sociodemographic, economic, and health-status-related characteristics. After adjustment for county-level characteristics, US counties with ≥70% of their adult population fully vaccinated against COVID-19 had 32% (95% CI: 19-43; P =<.001) and 39% (95% CI: 23-51; P =<.001) lower rates of COVID-19 cases and deaths, respectively, compared to counties that did not achieve 40% uptake. Similarly, US counties with 60-69% uptake had 14% (95% CI: 2-25; P =.023) and 19% (95% CI: 4-32; P =.017) lower rates versus those with <40% adult coverage. No impact was observed for counties with 40-49% or 50-59% uptake. Our results suggest that communities should continue to prioritize improving COVID-19 vaccination rates.
Comparing SARS-CoV-2 natural immunity to vaccine-induced immunity: reinfections versus breakthrough infections
[Preprint.] We conducted a retrospective observational study comparing three groups: (1)SARS-CoV-2-naïve individuals who received a two-dose regimen of the BioNTech/Pfizer mRNA BNT162b2 vaccine, (2)previously infected individuals who have not been vaccinated, and (3)previously infected and single dose vaccinated individuals. SARS-CoV-2-naïve vaccinees had a 13.06-fold (95% CI, 8.08 to 21.11) increased risk for breakthrough infection with the Delta variant compared to those previously infected, when the first event (infection or vaccination) occurred during January and February of 2021. The increased risk was significant (P<0.001) for symptomatic disease as well. SARS-CoV-2-naïve vaccinees were also at a greater risk for COVID-19-related-hospitalizations compared to those that were previously infected. This study demonstrated that natural immunity confers longer lasting and stronger protection against infection, symptomatic disease and hospitalization caused by the Delta variant of SARS-CoV-2, compared to the BNT162b2 two-dose vaccine-induced immunity.
Safety of the BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Setting
We used data from the largest health care organization in Israel to evaluate the safety of the BNT162b2 mRNA vaccine. For each potential adverse event, in a population of persons with no previous diagnosis of that event, we individually matched vaccinated persons to unvaccinated persons according to sociodemographic and clinical variables. In the vaccination analysis, the vaccinated and control groups each included a mean of 884,828 persons. Vaccination was most strongly associated with an elevated risk of myocarditis (risk ratio, 3.24; 95% confidence interval [CI], 1.55 to 12.44; risk difference, 2.7 events per 100,000 persons; 95% CI, 1.0 to 4.6), lymphadenopathy (risk ratio, 2.43; 95% CI, 2.05 to 2.78; risk difference, 78.4 events per 100,000 persons; 95% CI, 64.1 to 89.3), appendicitis (risk ratio, 1.40; 95% CI, 1.02 to 2.01; risk difference, 5.0 events per 100,000 persons; 95% CI, 0.3 to 9.9), and herpes zoster infection (risk ratio, 1.43; 95% CI, 1.20 to 1.73; risk difference, 15.8 events per 100,000 persons; 95% CI, 8.2 to 24.2). SARS-CoV-2 infection was associated with a substantially increased risk of myocarditis (risk ratio, 18.28; 95% CI, 3.95 to 25.12; risk difference, 11.0 events per 100,000 persons; 95% CI, 5.6 to 15.8) and of additional serious adverse events, including pericarditis, arrhythmia, deep-vein thrombosis, pulmonary embolism, myocardial infarction, intracranial hemorrhage, and thrombocytopenia. The vaccine was associated with an excess risk of myocarditis (1 to 5 events per 100,000 persons). The risk of this potentially serious adverse event and of many other serious adverse events was substantially increased after SARS-CoV-2 infection.
COVID-19 Vaccine in Pregnant and Lactating Women: A Review of Existing Evidence and Practice Guidelines
The continued exclusion of pregnant and lactating women from the COVID anti-viral and vaccine trials has created the paradox of a lack of empirical evidence in a high-risk population. Based on the experience of similar prior vaccines, animal developmental and reproductive toxicology studies, and preliminary findings from human studies, various healthcare professional advisory committees (Advisory Committee on Immunization Practices, American College of Obstetricians and Gynecologists, Society for Maternal-Fetal Medicine, and Academy of Breastfeeding Medicine) have issued guidance supporting COVID-19 vaccination in pregnant and lactating women. In this article, we summarize the available data on the efficacy and safety profile of COVID-19 vaccination in pregnant and lactating women, review the challenges of vaccine hesitancy, and include recommendations for healthcare providers.
