The US drug regulator on Friday added a warning to the literature that accompanies Pfizer Inc BioNTech and Moderna Covid-19 vaccine shots to indicate the rare risk of heart inflammation after its use.
For each vaccine, the fact sheets for healthcare providers have been revised to include a warning that reports of adverse events suggest increased risks of myocarditis and pericarditis, particularly after the second dose and with onset of symptoms within a few days after vaccination, the FDA said.
As of June 11, more than 1,200 cases of myocarditis or pericarditis have been reported to the US Vaccine Adverse Event Reporting System (VAERS), out of about 300 million mRNA vaccine doses administered.
The cases appear to be notably higher in males and in the week after the second vaccine dose. The CDC identified 309 hospitalizations from heart inflammation in persons under the age of 30, of which 295 have been discharged.
Health regulators in several countries have been investigating cases of myocarditis and pericarditis, more frequently found in young men, after a shot of Pfizer or Moderna, vaccines that are based on the mRNA technology.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
The latest update from FDA follows an extensive review of information and the discussion by CDC's Advisory Committee on Immunization Practices meeting on Wednesday.