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Dear Dr Ombeva,
My three-month-old son has a cough that is not clearing. We recently visited Nakuru but before the reports on news that there was an outbreak of flu disease in the town. Should I be worried that he may have caught the virus? Does he need to get the vaccine?
Thanks for your question. Before six months of age, an infant should be protected against influenza from antibodies from the mother, passed on to the body while in the womb and during breastfeeding. That is the reason the flu vaccine is given after six months of age. Flu is caused by influenza virus, and can be a serious disease that can lead to hospitalisation and sometimes even death.
An annual seasonal flu vaccine (either the flu shot or the nasal spray flu vaccine) is the best way to reduce chances of getting flu. Flu vaccines induce production of antibodies about two weeks after vaccination, which provide protection against infection with three flu viruses; an influenza A (H1N1) virus, an influenza A (H3N2) virus, and an influenza B virus.
Some flu vaccines made to protect against four flu viruses (called “quadrivalent” vaccines), which protect against the same viruses as the trivalent vaccine and an additional B virus. Vaccine is required annually because the body’s immune response from vaccination declines over time and secondly the flu viruses are constantly changing, thus vaccine is sometimes updated to keep up with changing flu viruses.
Therefore, for optimal protection, everyone six months and older should get vaccinated annually. Flu vaccine does not work right away, and it takes about two weeks after vaccination for antibodies to develop in the body and provide protection.
A person may still get flu even when vaccinated, since protection depends on age and health status of the person being vaccinated, and the similarity or “match” between the viruses used to make the vaccine and those circulating in the community, such that if the viruses in the vaccine and the influenza viruses circulating in the community are closely matched, vaccine effectiveness is higher, but if they are not closely matched, then vaccine effectiveness can be reduced.
Besides, even when viruses are not closely matched, the vaccine can still protect many people and prevent flu-related complications because antibodies made in response to the vaccine can provide cross-protection against different but related influenza viruses.
— Dr Ombeva Malande is a
paediatrics and child health expert