Are there any new problems with the most recent COVID-19 (Coronavirus Disease 2019) vaccine?

COVID-19 Vaccine Safety: Recent Surveillance Findings

The most recent 2024-2025 COVID-19 vaccines (targeting JN.1 and KP.2 strains) have identified two new statistical safety signals during surveillance: Guillain-Barré syndrome in adults ≥65 years and ischemic stroke in adults ≥50 years, though evidence remains inconclusive whether these represent actual risks, and any theoretical risk must be weighed against substantial benefits in preventing COVID-19 complications including stroke itself. 1

New Safety Signals Identified in 2023-2024 Season

The CDC's Vaccine Safety Datalink (VSD) surveillance identified two prespecified safety signals for mRNA COVID-19 vaccines that had not been previously observed: 1

• Guillain-Barré syndrome (GBS) emerged as a signal among persons aged ≥65 years during the 2023-2024 vaccine season 1

  • This association had not been identified in prior COVID-19 vaccine formulations 1
  • Current evidence is inconclusive as to whether this signal represents an actual risk 1

• Ischemic stroke was detected among adults aged ≥50 years 1

  • A similar signal was previously observed with the bivalent formulation and reviewed by ACIP in October 2023 1
  • Cumulative data to date have not provided clear and consistent evidence of a safety problem for ischemic stroke 1
  • A follow-up VSD study is currently in progress to further assess this risk 1

Context: Known Safety Profile

Established Adverse Events

The pre-specified adverse events that continue to be monitored include: 1

• Myocarditis and pericarditis remain the most well-established serious adverse events, particularly after mRNA vaccines 1

  • Risk is highest after the second dose in young males aged 12-29 years, with 39-47 cases per million vaccinated 2, 3
  • Most cases are mild and self-limiting 3
  • The certainty assessment for myocarditis/pericarditis remains low for adults and adolescents, and very low for children 1

• Anaphylaxis occurs at extremely low rates (0.0003% or 2.5-4.7 cases per million doses) 2, 4

Overall Safety Assessment

• The certainty of evidence for prespecified adverse events remains low for adults and adolescents, and very low for infants and children 1
• Most adverse events are mild to moderate (grade 1-2), with the most common being injection site pain, fatigue, myalgia, headache, and fever 2, 3
• Serious adverse event rates remain extremely low across all vaccine platforms 4

Critical Risk-Benefit Analysis

The benefits of COVID-19 vaccination substantially outweigh any identified or theoretical risks: 1

• For every 1 million males aged 12-29 years receiving a second mRNA dose, while 39-47 myocarditis cases would be expected, vaccination would prevent 560 hospitalizations, 138 ICU admissions, and 6 deaths 2, 3
• Any real or theoretical risk of vaccine adverse events, including the new stroke signal, must be placed in context that COVID-19 itself causes stroke and other serious complications 1

Clinical Implications for Practice

Surveillance and Reporting Requirements

Vaccination providers are required to report to VAERS: 1

• Vaccine administration errors
• Serious adverse events
• Cases of multisystem inflammatory syndrome
• Cases of myocarditis or pericarditis
• COVID-19 cases resulting in hospitalization or death after vaccination

Evaluation of Concerning Symptoms

For chest pain occurring early after mRNA vaccination: 2, 3

• Obtain ECG, cardiac troponin, and echocardiogram
• If myocarditis is suspected, obtain cardiology consultation and consider cardiac MRI

For neurological symptoms post-vaccination:

• Maintain heightened awareness for GBS symptoms in adults ≥65 years 1
• Evaluate stroke symptoms promptly in adults ≥50 years, recognizing that COVID-19 infection itself carries stroke risk 1

Current Recommendations Remain Unchanged

Despite these surveillance signals, ACIP continues to recommend 2024-2025 COVID-19 vaccination for all persons aged ≥6 months to target currently circulating strains and provide protection against severe illness and death. 1, 5