How did single-dose H1N1 vaccines change vaccination efforts during the pandemic?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Caring for flu victims — influenza pandemic (H1N1) of 2009 Doctors at the Mexico City Navy Hospital wearing protective gear as they tend to patients complaining of H1N1 flu-like symptoms.

The development of single-dose vaccines significantly improved the response to the 2009 H1N1 pandemic by addressing critical manufacturing and timing constraints. Initial vaccine candidates required two doses administered three weeks apart, creating concerns that global supplies would be insufficient and that immunity would not develop quickly enough to counter the anticipated fall wave of the virus.1

By September 2009, pilot tests of single-dose vaccines—developed by companies such as Novartis AG—demonstrated that one injection could provide sufficient protection for adolescents and adults. This breakthrough allowed for more efficient mass production and distribution, which were considered vital to stemming the spread of the illness. To support global efforts, the World Health Organization aimed to secure 200 million donated doses for low- and middle-income countries.1

While a single dose was sufficient for most, two doses remained the recommendation for children between six months and nine years of age. Despite the success of these vaccination efforts, public wariness persisted, particularly after some vaccines were later linked to an increased risk of narcolepsy in specific populations.1