According to the US Centers for Disease Control and Prevention, the interval between the first and second doses of Pfizer and the Modenacovid-19 vaccine can be as long as eight weeks for certain people. Vaccine guidance Updated on Tuesday.
Previous guidance stated that the second vaccination should be given 3 weeks after the first vaccination with the Pfizer vaccine or 4 weeks after the first vaccination with the Moderna vaccine. According to the CDC, the vaccine remains safe and effective at the original interval, but extending the interval may reduce the risk of myocarditis, a type of heart inflammation, in some populations. Rare cases of myocarditis have been reported primarily after the second dose of the mRNA Covid-19 vaccine, with men aged 12-29 years being at greatest risk.
“Although the absolute risk remains small, the relative risk of myocarditis is higher in men aged 12 to 39 years, and this risk may be reduced by increasing the interval between the first and second doses.” Said the CDC, focusing on several studies of the elderly. More than 12 people have shown that “a small risk of myocarditis associated with the mRNA COVID-19 vaccine is reduced, and peak antibody response and vaccine efficacy may increase at intervals longer than 4 weeks.”
“The 8-week interval may be optimal for some people over the age of 12, especially men between the ages of 12 and 39,” said the new guidance.
According to the CDC, for people with moderate or severe immunodeficiency, adults over the age of 65, and “people who need immediate protection due to increased risk of community infection or serious illness”, 3 Weekly or 4-week intervals are still recommended. Since there are no data on children under the age of 11, this group recommends receiving a second Pfizer vaccine 3 weeks after the first dose.
Booster doses continue to be recommended for most people 5 months after the double dose primary series of mRNA vaccines or 2 months after the Johnson & Johnson single dose primary vaccination.
At a meeting of the CDC’s Independent Immunization Implementation Advisory Board earlier this month, authorities suggested updating guidance recommending longer intervals between first and second doses of the mRNA vaccine.
Dr. Sara Oliver, Head of Epidemic Intelligence Service at the CDC’s Viral Diseases Division, told the Commission that the incidence of myocarditis decreases as the interval between the first and second doses increases. Still, the benefits of vaccination with Pfizer or Moderna vaccines are clear, regardless of the time between shots, she said.
“The benefits of both mRNA vaccines far outweigh the risk of myocarditis compared to the absence of the vaccine,” Oliver said.