The United States Centers for Disease Control and Prevention (CDC) has updated its recommendations for mRNA vaccines against COVID-19, increasing the recommended time between the initial two doses of the vaccine to up to eight weeks for certain categories of people.
The recommended interval between the two vaccine doses was previously three weeks for the Pfizer-BioNTech vaccine and four weeks for the Moderna vaccine.
The safety and effectiveness of these vaccines given at the originally recommended intervals remains valid, the CDC said. However, allowing more time between the first two doses of the COVID-19 mRNA vaccine may reduce the risk of myocarditis, a type of heart inflammation, in certain populations.
“Although the absolute risk remains low, the relative risk of myocarditis is higher in men aged 12 to 39, and this risk could be reduced by increasing the interval between the first and second dose”, according to the recommendations of the CDC updates Tuesday.
“An eight-week interval may be optimal for some people 12 years and older, particularly for male patients 12 to 39 years old,” the new guidelines state.
A reduced time interval between the first and second dose, three weeks for a Pfizer-BioNTech vaccine and four weeks for a Moderna vaccine, remains the recommended interval for people with immunodeficiency, people aged 65 and over. more, and people in need of rapid protection against the coronavirus, according to the CDC.