Vaccines are effective against severe cases of Covid-19 ?in children and adolescents, according to a review of studies. However, the study published in the journal BMJ Paediatrics Open shows that with most children already infected with the SARS-CoV-2 virus and building up a natural immunity, the additional benefit of vaccination in healthy children is minimal.

The team, led by researchers at the Murdoch Children's Research Institute in Australia, explored the challenges and considerations of Covid-19 vaccination, especially in low- and middle-income countries with high levels of community transmission and infection-derived immunity.

The review found that any roll-out of Covid-19 vaccines in low- and middle-income countries should also complement routine childhood vaccine programmes that have a greater impact on illness and death, including for measles, pneumonia and diarrhoeal disease. The study shows that despite most children having been infected and severe infection could occur, deaths were extremely rare in children.

Globally, 16,100 Covid-19 deaths have been reported in those up to 19 years old, according to the researchers. They highlight that although Covid-19 vaccinations in children were effective at the time they were tested, the benefits were lower in the current context of high infection-derived immunity.

The study found that the extra gain was also much lower compared to other life-saving vaccines in low- and middle-income countries, where childhood deaths from other vaccine preventable diseases were considerably higher.?The review noted many countries have still not introduced proven lifesaving vaccines, including pneumococcal, rotavirus and human papillomavirus, into their immunisation schedules.

The resources required for Covid-19 vaccine roll-out in these countries posed a considerable challenge, it stated. John Hart from Murdoch Children’s Research Institute said although there was not strong evidence to support routine vaccination of all healthy children, it was a different for high-risk children, especially those with disabilities and certain underlying conditions.

"Given the very high prevalence of risk factors for severe Covid-19 in low- and middle-income countries, vaccination against Covid-19 is an important consideration in all age groups, including children,” he said. However, decisions should be made considering the direct benefits to the individual child, not broader benefits to the household or community related to transmission, particularly as the effectiveness of the vaccines against infection is temporary, the researchers said.

Professor Fiona Russell from Murdoch Children's said there was also a lack of public health data in low- and middle-income countries, which underscored the importance of ensuring equitable access to safe and effective vaccines for future epidemics before exposure to infection. "In low- and middle-income countries, most people were infected by the time vaccines became available, highlighting the profound inequity in global vaccine distribution," she added.