Current data does not indicate that COVID-19 booster shots are needed, the World Health Organization (WHO) said on Wednesday, adding that the most vulnerable people worldwide should be fully vaccinated before high-income countries deploy a top-up.

The comments came just before the U.S. government said it planned to make the booster shots widely available to all Americans starting on Sept. 20 as infections from the Delta variant of the coronavirus rise.

WHO chief scientist Soumya Swaminathan, asked about the need for boosters to increase protection against the disease, told a Geneva news conference: "We believe clearly that the data today does not indicate that boosters are needed."

Further research was needed, she added.

WHO senior adviser Bruce Aylward, referring to booster shots being administered in high-income countries, told reporters: "There is enough vaccine around the world, but it is not going to the right places in the right order."

COVID-19 Vaccine

Frequently Asked Questions

How does a vaccine work?

A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.

How many types of vaccines are there?

There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.

What does it take to develop a vaccine of this kind?

Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.

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Two doses should be given to the most vulnerable worldwide before boosters are administered to those fully-vaccinated, he said, adding: "We are a long, long way from that."

Follow our full coverage of the coronavirus pandemic here.

No need for COVID booster jabs for now: WHO

WHO chief scientist Soumya Swaminathan, asked about the need for boosters to increase protection against the disease, told a Geneva news conference: 'We believe clearly that the data today does not indicate that boosters are needed.'