New York, Mar 16 (IANS): Nearly everyone who got their first dose of a two-shot Covid-19 vaccine got their second dose within the recommended window in the US, according to new data from the Centers for Disease Control and Prevention (CDC).

According to a report in The Verge, during the first two months of the US Covid-19 vaccination campaign, around 12 million people got their first dose and were also scheduled for their second dose.

The second dose is supposed to be given three weeks after the first for the Pfizer-BioNTech vaccine and four weeks for the Moderna vaccine (with a few days' buffer on each side). In that group, 88 per cent of people had their second shot on schedule.

Around 9 per cent of people who had their first shot between December 14 and February 14 had not yet received their second dose but were still within 42 days from their first dose, the report said.

The CDC said that when a delay is unavoidable, people can wait that long. Three percent of people were outside of the 42-day window and had missed the dose, it added.

To look at those numbers in a different way, the CDC also looked at everyone who'd received a second dose during those two months to see how many people received it within the recommended period.

Over 95 per cent of people were on schedule. Just under 3 per cent of people were late (but within the 42-day window), and 1.5 per cent of people had their second injection early.

Such high numbers of people getting their second dose -- and getting it on time -- are reassuring, the CDC wrote in its report.

The Pfizer-BioNTech and Moderna vaccines may have some protection with just one dose, but a single dose wasn't part of the clinical trials, and it's not clear how long that protection might last, the report said.

The second shot boosts the immune system and gives people the full benefits of the vaccines.