People who are not vaccinated against COVID-19 were 11 times more likely to die of the disease and 10 times more likely to be hospitalised, according to one of the three major studies published by the US Centers for Disease Control and Prevention (CDC) on Friday.

For the first study, the CDC examined more than 600,000 Covid cases reported across the US from April to July, when the Delta was at its peak, according to NBC news.

A second study, on vaccine effectiveness, looked at more than 1,000 COVID-19 hospitalisations. Some of those infections occurred earlier in April, when the alpha variant was circulating widely. Others occurred from July through August, when the delta variant was at its peak.

The study showed that the COVID-19 vaccines were highly effective, more than 90 percent, against hospitalisation among those who are under 65. While the protection seemed to wave a bit for those above 65, it was just under 90 percent.

The third study had similar findings, which showed that the vaccines' effectiveness was high against hospitalisation - 86 percent. However, that effectiveness was a bit lower for among those over 75, at 76 percent, according to NBC News.

For the third study, the assessment was based on the largest US study till date of the real-world effectiveness of the three vaccines, based on 32,000 people who were hospitalised or had visited urgent care clinics for any reason from June through early August.

"The bottom line is this: We have the scientific tools we need to turn the corner on this pandemic. Vaccination works and will protect us from the severe complications of covid-19," CDC Director Rochelle Walensky was quoted as saying by The Washington Post at a White House coronavirus briefing on Friday.

The US Food and Drug Administration are scheduled to meet to discuss the safety and effectiveness of a third dose next week and the findings of the research is likely to be scrutinized then, according to reports.

(With inputs from NBC News & The Washington Post.)