According to the World Health Organization's (WHO) vaccine advisory panel, individuals who are immunocompromised or have received an inactivated vaccination should have a booster dose of a COVID-19 vaccine.

Many countries have been administering booster doses to the elderly and others with underlying health problems, but concerns about the new Omicron variant have spurred some to extend their usage to a larger population.

With vaccination rates in much of the developing world worryingly low, the WHO has recently stated that primary doses, rather than boosters, should be prioritised. The recommendation comes following a meeting on Tuesday of the Strategic Advisory Group of Experts (SAGE) on Immunisation to assess the necessity for COVID-19 boosters.

Poorest countries can expect vaccines within weeks: WHO – EURACTIV.com

Emerging findings, according to SAGE chair Alejandro Cravioto, suggest that vaccine efficacy against COVID-19 is waning, with a considerable reduction in older people in particular.

According to Kate O'Brien, director of the WHO's immunisation division, COVID-19 vaccines protect "very well" for six months after the last dose, with some "minor, modest decline" in protection.

Sinovac Biotech, state-owned Sinopharm, and India's Bharat Biotech develop inactivated vaccines, which use chemicals, heat, or radiation to inactivate or destroy the SARS-CoV-2 virus.

Although a single dosage of the Johnson & Johnson vaccine is still effective, Cravioto claims that data from the company's clinical trials using two doses clearly demonstrate the benefit of having more vaccinations.