According to findings from a UK trial, COV-BOOST, fourth doses of COVID-19 vaccines have shown an increase in protection against the virus, especially in those over the age of 70.

However, scientists have cautioned that any short-term protection against infection is unlikely to be sustained.

In April 2022, the UK made fourth doses available to the over-75s age group and to those most vulnerable. Countries such as Germany and Israel have already begun to offer all adults a fourth dose.

Any further decisions on whether to offer boosters to a larger part of the population in the autumn will take into consideration whether new sub-variants are spreading, and what the level of added pressure is from COVID-19 on hospitals and the care system.

The COV-BOOST study, involving 133 people, showed that two weeks after their fourth dose, the vaccines were ‘well-tolerated’ and ‘boosted immunity’.

Despite this, the study – published in The Lancet Infectious Diseases – summarised that a considerable increase in anti-spike antibodies would probably wane rapidly, as was demonstrated after third doses.

Participants involved in the study included 70-year-olds and some aged under 70, with all involved receiving a dose of the Pfizer vaccine or a half dose of the Moderna vaccine around six months after having had their third dose.

Emerging estimates from the World Health Organization (WHO) indicate that the full death toll associated – directly or indirectly – with the COVID-19 pandemic between 1 January 2020 and 31 December 2021 was approximately 14.9 million.

The calculation was made by focusing on ‘excess mortality’ which is deduced as the difference between the number of deaths that have occurred and the number that would have been expected had there not been an international pandemic.

Excess mortality also includes deaths associated with COVID-19 due to the pandemic’s impact on health systems and wider society.

Deaths linked indirectly to COVID-19 are often attributable to other health conditions for which people were unable to access treatment because systems were overburdened by the pandemic.

The estimated number of excess deaths can also be influenced by other considerations such as deaths averted during the pandemic due to lower risks of certain events, like motor-vehicle accidents or occupational injuries.

The majority of excess deaths – 84% – were concentrated in South-East Asia, Europe and the Americas, while 68% of excess deaths were concentrated in just ten countries globally.

The estimates for the 24-month period included a breakdown of excess mortality by age and gender. They confirmed that the global death toll was higher for men than women – 57% male and 43% female – and higher among older adults.