No Added Adverse Event Risk in Pfizer-BioNTech COVID-19 Vaccine

For pharmacists counseling patients this respiratory season, a new safety study offers reassurance that the 2024–2025 Pfizer-BioNTech KP.2 COVID-19 vaccine (BNT162b2) was not linked with an increased risk of any of the 20 pre-specified adverse events of special interest (AESI), as noted by researchers in a study published in Vaccine.¹

“Safety of the original BNT162b2 COVID-19 vaccine has been well characterized, with myocarditis/pericarditis identified as a risk following vaccination,” according to authors of the study. “No new safety concerns have been identified in the 2023–2024 variant-adapted COVID-19 vaccines, as demonstrated in several large-scale safety surveillance studies in the US and Europe that the safety profile remains consistent with the original formulations.”

The observational study evaluated 89,485 commercially insured individuals aged 6 months and older who received the 2024-2025 BNT162b2 KP.2 vaccine between August 2024 and March 2025. Utilizing a self-controlled risk interval design, researchers compared the incidence of 20 pre-specified conditions during post-vaccination risk windows against subsequent control windows.¹

READ MORE: Harms of Public Health Measures Overlooked in COVID-19 Policy Reviews

Monitored conditions included acute neurological events, cardiovascular complications, immune-mediated conditions, and systemic inflammatory disorders. Although point estimates were slightly higher during the risk period for non-febrile seizures and herpes zoster, these differences were not statistically significant.

Furthermore, no adverse event met the pre-defined threshold for a safety signal. Notably, 75.6% of participants received a seasonal influenza vaccine on the same day as their COVID-19 shot, maintaining a consistent safety profile.¹

Robust Real-World Data on Protection Against Severe Outcomes

This reassuring safety profile is backed by comprehensive real-world evidence evaluating both vaccine safety and clinical effectiveness.^2,3

A target trial emulation study of 538,631 matched veteran pairs within the Veterans Health Administration demonstrated that the 2024-2025 KP.2 COVID-19 vaccine achieved 65.53% effectiveness against COVID-19–associated mortality overall and 69.77% protection among adults aged 75 years and older.³

Global surveillance by Pfizer and BioNTech reinforces these findings across more than 5 billion distributed doses, supported by 22 clinical trials and 12 postmarketing safety studies. Although vaccine effectiveness against mild infection is modest and wanes over time, protection against fatal outcomes remains durable.^2,3

Navigating Variant Shifts and Regulatory Strain Updates

Continuous safety and effectiveness surveillance remains essential as SARS-CoV-2 evolves into new lineages. CDC surveillance reports highlight the emergence of divergent subvariants such as BA.3.2 and XFG, testing vaccine-induced immunity. In response to shifting epidemiological patterns, regulatory bodies like the FDA advisory committee recently recommended updated monovalent formulations to match circulating strains.^3,4

CDC VISION network data confirm that seasonal immunizations continue to prevent substantial hospitalizations and emergency department visits even as viral strains drift. Public health agencies increasingly rely on wastewater surveillance as an early warning system to anticipate viral shifts weeks before clinical diagnostic surges.⁴

Empowering Pharmacists to Address Patient Hesitancy

As accessible community providers, pharmacists play a central role in guiding patients through booster recommendations and addressing vaccine hesitation. Pharmacy experts emphasize that mRNA technology rests upon decades of research, including pivotal 2005 discoveries showing that modified nucleosides suppress inflammatory responses while enabling antigen production.^5,6

To contextualize rare risks, Mohamed A. Jalloh, PharmD, notes that the estimated rate of post-vaccination myocarditis equals roughly 2 individuals in a sold-out stadium of 100,000 spectators. Furthermore, clinical ambulatory care pharmacist Darren Mensch, PharmD, recommends employing the AIMS framework consisting of Announcing recommendations, Inquiring about concerns, Mirroring patient perspectives, and Securing trust to foster informed decisions.

Looking ahead, the mRNA platform is expanding beyond respiratory viruses into combination vaccines for influenza and respiratory syncytial virus, as well as personalized cancer immunotherapies. By translating complex surveillance data into empathetic patient conversations, pharmacists serve as the vital bridge between biotechnology innovation and public health confidence.^5,6

“There was no increased risk of 20 pre-specified AESIs following 2024–2025 BNT162b2 COVID-19 vaccination among commercially insured individuals aged ≥6 months in the US,” concluded authors of the current study.¹ “Furthermore, no new safety signals were identified. Ongoing safety monitoring with longer follow-up will expand upon these findings.”

READ MORE: COVID-19 Resource Center

REFERENCES

1. Sun J W., Dodge L E., Cai S, et al. Monitoring of adverse events following 2024–2025 BNT162b2 KP.2 COVID-19 vaccination in the United States. Vaccine. 2026;95. doi:10.1016/j.vaccine.2026.129296

2. 2025-2026 COVID-19 vaccine formula: Pfizer/BioNTech supportive data. FDA. May 22, 2025. Accessed October 26, 2026. https://www.fda.gov/media/186597/download

3. Ioannou GN, Berry K, Yan L, et al. Effectiveness of the 2024–2025 KP.2 COVID-19 vaccines in the United States during long-term follow-up. Nat Commun. 2025;17(1):1043. doi:10.1038/s41467-025-67796-0

4. Gallagher A. CDC will focus on BA.2.3 COVID-19 variant for upcoming respiratory season. Drug Topics. June 6, 2026. Accessed October 26, 2026. https://www.drugtopics.com/view/cdc-will-focus-on-ba-2-3-covid-19-variant-for-upcoming-respiratory-season

5. Nowosielski B, Mensch D. FAQ: pharmacist understanding of mRNA vaccine technology. Drug Topics. September 29, 2026. Accessed October 26, 2026. https://www.drugtopics.com/view/pharmacist-understanding-of-mrna-vaccine-technology

6. Gallagher A. The effects of COVID-19 influencing the development of vaccines. Drug Topics. August 10, 2026. Accessed October 26, 2026. https://www.drugtopics.com/view/the-effects-of-covid-19-influencing-the-development-of-vaccines