Have you noticed that when you was sick from the flu it wasn't as severe as maybe the person who was infected before you and after you? Or vice versa, you became severely ill when everybody else was better in no time? Scientist say the reason for this is that exposure to the flu virus during childhood give us a partial protection for the rest our lives against distantly related influenza viruses. The term for this is called immunological imprinting. Research in 2016 dispelled the myth that previous exposure to the flu did not protect you against future strains that could mutate from animals to humans.
A PLoS Pathogen study was able to solve a problem that for decades had scientist puzzled on why the influenza virus affected people at various degrees.The study was able to examine two subtypes of the influenza virus: H3N2 and H1N1. H3N2 cause the most deaths and tend to affect the elderly. H1N1 affects young children and middle-aged adults. It was determined that if you was infected with H1N1 as a child, you was less likely to experience severe sickness later in life when re-infected compared to those who was first infected by H3N2. People who was first infected by H3N2 had extra protection against H3N2 later in life. However, scientist were perplexed when they was unable to figure out why people who was exposed to H2N2, a distant related cousin to H1N1, was not protected against H1N1 later in life. They hope that by solving this mystery it will lead them to creating the first universal vaccine.
It is key to note that secondary exposure to a flu strain do not give you the extra protection against future infections as does your first exposure. Being infected by a different subtype later in life will not give the extra protection you received as a child. Scientist hope that by studying the sequence in which people are infected by the influenza virus they will be able to predict who will need to be treated based on the subtype that is circulating at the time. This will help improve the response on who will need to be vaccinated the most.
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