(CNN) The US Food and Drug Administration is planning on allowing Americans to receive a different coronavirus vaccine for their booster shots than their original dose, according to two sources familiar with the current thinking inside the agency.
While the details on exactly what language the FDA will use remains unclear, it's expected to make a broad authorization on "mixing and matching" potentially as soon as this week.
While this could apply to all FDA-authorized vaccines in the US, officials realize it has been the biggest concern for those who received a single dose of the Johnson & Johnson vaccine.
The FDA has already authorized boosters of the Pfizer Covid-19 vaccine for some adults, and is currently considering authorization of boosters of the Moderna and Johnson & Johnson vaccines. The US Centers for Disease Control and Prevention's vaccine advisers are scheduled to meet Thursday to discuss Moderna and J&J boosters.
The National Institutes of Health last week presented to the FDA's vaccine advisers early information from an ongoing study showing that it didn't matter which vaccine people got first and which booster they got -- it was safe to mix boosters and it revved up immune response. Mixing boosters also provided a good response to the Delta variant.