Younger people 'should get swine flu vaccine first'

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Younger people 'should get swine flu vaccine first'

BMJ Group, Tuesday 30 June 2009 00.00 BST

Young adults who got swine flu in Mexico were more likely to get serious

complications or die than older people who may have a natural immunity,

researchers say. They suggest that once a vaccine against swine flu is

developed, younger people could be given priority, if there is insufficient

vaccine to protect everyone.

What do we know already?

In previous world-wide outbreaks of flu (pandemics), younger people have

been more seriously affected than older people. That's one of the unusual

things about a pandemic - it turns the usual situation upside down, where

seasonal flu tends to be more serious for older people.

Seasonal flu, although very unpleasant, tends not to cause long-term

problems for healthy adults. But when older people, or those with health

problems, get seasonal flu, it may cause serious illness such as pneumonia.

When there's a seasonal flu outbreak, older people are more likely to die as

a result of complications like pneumonia.

Researchers are looking at the current pandemic of H1N1 (swine) flu, to see

how it compares to previous seasonal flu outbreaks. They are concentrating

on the early months of the outbreak in Mexico, during March and April this

year. They want to see who was affected, how seriously, and consider what

that tells us about how best to fight the disease. The new study compares

figures from this year with seasonal flu outbreaks in Mexico since 2005.

What does the new study say?

The figures show:

A sudden increase in the numbers of people falling ill with flu in March

2009, outside the normal flu season (which usually runs roughly from

November to February)

A sudden increase in the numbers of adults aged 20 to 45 getting severe

pneumonia or dying as a result of flu

A comparative decrease in the numbers of over-65s getting severe pneumonia

or dying as a result of flu.

During previous outbreaks of seasonal flu in Mexico, most of the people who

died were either very young or old. Usually, only 17 in 100 deaths from flu

happen to people aged five to 59. But in this outbreak, 87 in 100 deaths

from flu happened to people in this age group. And the people most likely to

get severe pneumonia from flu in this outbreak were young adults, aged 25 to

44.

The researchers say these figures are in line with the early months of

previous outbreaks of pandemic flu, such as the one in 1918. They say that

older people (those born before 1957) might have some immune protection from

the H1N1 virus, because similar flu viruses were common during their

childhood. That might mean their immune systems are already primed to fight

off the virus, which could be why they are less likely to have severe

complications than younger people.

Because older people may have natural immunity, the researchers suggest

vaccines against the H1N1 flu could be targeted at younger people, if there

s not enough to go around.

How reliable are the findings?

The researchers say they can't be sure of the exact figures, because many

people with flu may not have sought medical help, or hospitals may not have

reported all their cases. But they say that the figures showing a bigger

proportion of deaths from flu in younger adults are likely to be reliable.

Where does the study come from?

The study was carried out by researchers from a number of universities in

Mexico and the US. It was published in the New England Journal of Medicine,

owned by the Massachusetts Medical Society. It was paid for by the Ministry

of Health and National Institute for Public Health in Mexico.

What does this mean for me?

Although there have been around 6,000 confirmed cases of H1N1 swine flu in

the UK, the majority of them have been mild. The UK has not had hundreds of

severe pneumonia cases, as happened in Mexico earlier this year. We can't

rule out an increase in the numbers of severe cases, though.

This research suggests that people born before 1957 might have some natural

protection from the virus. But this paper looks at figures from Mexico, so

we don't know whether older people in the UK have the same protection.

What should I do now?

There's no need to take any action as a result of this study. To avoid

catching swine flu, or any other type of respiratory illness, the best thing

you can do is take sensible hygiene precautions, such as washing your hands

frequently.

From:

Chowell G, Bertozzi SM, Colchero MA, et al. Severe Respiratory Disease

Concurrent with the Circulation of H1N1 Influenza. New England Journal of

Medicine. Published online, June 29 2009