COVID-19 mRNA Vaccines Maintain Strong Protection Against Severe Illness
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Recently, discussions have intensified in the United States and globally regarding vaccine boosters for those who have already received initial doses. Early this year, experts began raising concerns about the duration of antibody protection following the first and second doses of vaccination.
As additional research emerged, findings indicated a notable decrease in effectiveness for the Pfizer/BioNTech vaccine, alongside a moderate decline for other vaccines.
Quoting Joe Duncan’s analysis on Pfizer's diminishing effectiveness from earlier this year:
> Current data indicates that the Moderna vaccine’s effectiveness has only slightly decreased, from 86% to 76%. In contrast, the Pfizer vaccine has fallen from 76% to a mere 42%, aligning more closely with recent findings from Israel.
Subsequent reports have consistently confirmed that Pfizer’s protective effects diminish over time. Current evidence suggests that the Pfizer/BioNTech vaccine remains effective for most individuals until approximately seven months post-second dose, after which antibody levels significantly drop, leading to reduced protection.
Importantly, there has been no indication that this vaccine loses its effectiveness against severe disease.
Skepticism exists among some individuals regarding the cautious stance of health authorities like the CDC and FDA, who have been slow to recommend widespread booster shots. As it stands, the FDA has authorized Pfizer boosters for individuals aged 65 and older, as well as those in high-risk categories, particularly the immunocompromised.
Concerns arise that public health leaders are not adhering strictly to the data, referencing Israeli and Qatari studies that suggest vaccine effectiveness may be lower than reported.
Insights from Israel
You may recall alarming reports from Israel indicating that over 60% of hospitalized patients were fully vaccinated. Some media outlets exaggerated this figure, claiming that 95-99% of hospitalized patients were vaccinated, which is inaccurate.
Such statistics are expected in a highly vaccinated population. For instance, if 90% of a given demographic were women, it wouldn’t be surprising to find that 90% of hospitalizations were also among women, as this reflects the demographic makeup rather than a causal relationship.
Interestingly, the 60% hospitalization rate among vaccinated individuals in Israel, a country with a 78% vaccination rate, highlights the vaccine's effectiveness. Most hospitalized patients were over the age of 60, suggesting that the vaccine works well for those under 60.
The American Perspective
Dr. Paul Offit, a leading vaccine expert at the FDA, remarked on CDC data:
> There’s been no evidence of significant erosion of protection against severe disease.
Dr. Megan Ranney, an emergency medicine professor at Brown University, emphasized the importance of the current vaccine doses:
> The existing vaccines continue to provide strong protection against hospitalization and death. We are not back to the early days of the pandemic for those who have not yet received boosters.
New Findings from Pfizer
A recent retrospective cohort study published in The Lancet supports this assertion, revealing that while the vaccine’s effectiveness against infection may decline, it continues to protect against severe illness.
This study investigated the efficacy of the BioNTech/Pfizer vaccine against the delta variant (B.1.617.2) in the United States, analyzing health records from patients within the Kaiser Permanente Southern California healthcare system.
Study Overview
Kaiser Permanente Southern California encompasses approximately 4.7 million members from diverse backgrounds. Notably, Los Angeles County, the most populous in the U.S., has a population larger than all states except ten. If it were a state, it would rank as the 11th most populous.
Researchers focused on members with at least one year of healthcare coverage to ensure comprehensive medical histories. The initial sample included 4,920,549 participants, but only 3,436,957 met the criteria of being 12 years or older and having a medical history of at least one year.
The study period stretched from December 14, 2020, to August 8, 2021, allowing researchers to assess the effectiveness of the vaccine against various emerging variants.
Study Results
Overall, the vaccine exhibited a 91% effectiveness against variants other than delta. However, against the delta variant, protection dropped to 75%. In the first month post-vaccination, the vaccine was 93% effective against delta and 97% effective against other variants. Unfortunately, by four months, efficacy declined to 53% against delta and 67% against other variants.
Regarding hospitalizations, the vaccine maintained a high effectiveness rate, preventing approximately 90-93% of COVID-19-related hospitalizations throughout the study period.
The study concluded:
> Among fully vaccinated individuals, vaccine effectiveness against hospital admissions was 93% for delta and 95% for other variants.
Furthermore, the findings suggested:
> This retrospective cohort study indicated that those fully vaccinated with BNT162b2 [Pfizer’s mRNA vaccine] had an overall effectiveness of 73% against SARS-CoV-2 infections and 90% against COVID-19-related hospital admissions, with effectiveness against infections declining over six months. However, protection against hospital admissions remained high throughout the study.
Many in America are anxiously awaiting further studies to confirm that protection against hospitalization remains robust beyond the six-month period.
While 93% effectiveness against hospitalizations still leaves 7% at risk, the study’s authors were only able to confirm sustained high protection for six months. Additional studies will be necessary to ascertain long-term efficacy.
The authors also acknowledged funding from Pfizer, which prompts some to question the impartiality of the findings. Nonetheless, this data aligns with Israeli reports, helping to create a clearer understanding of the vaccine's performance.
Despite the absence of a double-blinded randomized control trial, this study sheds light on the cautious approach we should consider moving forward, as some experts have started to question the feasibility of achieving herd immunity.
I anticipate that boosters will eventually be approved for the broader American population, hoping that the maturation of antibodies will enhance our immune response against COVID-19.
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