London, Sep 10 (IANS): The UK's health regulator has approved Pfizer and AstraZeneca vaccines for booster doses against Covid-19, even as the country's decision on the third dose remains pending.

"We know that a person's immunity may decline over time after their first vaccine course. I am pleased to confirm that the Covid-19 vaccines made by Pfizer and AstraZeneca can be used as safe and effective booster doses," said June Raine, MHRA Chief Executive of Medicines and Healthcare products Regulatory Agency (MHRA), in a statement on Thursday.

The decision follows a careful review of available data on safety and effectiveness of booster or supplementary vaccine doses by the MHRA and the independent Commission on Human Medicines (CHM), which advises the government, it added.

The MHRA also noted that it is now up to the Joint Committee on Vaccination and Immunisation (JCVI), the UK vaccine advisory body, "to advise on whether booster jabs will be given and if so, which vaccines should be used".

The JCVI is awaiting results on seven different booster vaccines, which is expected this week.

However, the JCVI has said a third dose should be offered to people with severely weakened immune systems, which make up about half a million people over the age of 12 in the UK.

Earlier this week, Ministers said the National Health Service (NHS) was ready to go if booster jabs were given the green light.

But, AstraZeneca chief Pascal Soriot warned against rushing into a nationwide rollout noting that it may put extra pressure on the country's already burdened NHS.

Writing in The Telegraph, he said that a third dose of vaccines against Covid-19 may not be needed for everyone in the UK.

Moreover, the decision to jab the entire population must be based on "real world clinical effectiveness data, not simply antibody measurements", Soriot wrote in the newspaper.

On the other hand, US pharmaceutical major Pfizer's CEO Albert Bourla had said that Covid vaccine recipients will "likely" need a third dose between six to 12 months after they're fully inoculated.

He also suggested the need for yearly vaccinations against coronavirus.

The US is also expected to soon roll out Covid booster vaccines for all its citizens, even as the World Health Organization has called for a moratorium on boosters.

The US has already started a third dose for immunocompromised people.

Other countries that started booster vaccines include Israel, Italy, France, and Russia.