Swine flu vaccination - What you need to know

By Lorena Tonarelli MSc

Swine flu vaccination is finally under way. And just in time. After a period of slower activity, at the end of the summer, the 2009 H1N1 virus has started spreading again, and the number of swine flu cases is climbing.

Priority groups

Millions of doses of the vaccine are now available – nearly 11.5 million in the US, as of mid-October, according to the Centers for Disease Control and Prevention (CDC). They will be offered first to:

• Health care staff.
• Pregnant women.
• People who care for, or live with, babies younger than six months. This is particularly important, as babies below six months of age cannot receive the vaccine, so they are among the most vulnerable, because they are unprotected.
• Babies and young children aged 6 months to 4 years.
• Children and adults aged 5 to 18 years with underlying medical problems (asthma, diabetes, liver disease, etc.) or damaged immune systems (chemotherapy patients, AIDS sufferers, and those on steroids).

Then, it will be the turn of everyone aged 18 to 64.

Two types

The H1N1 flu vaccine can be administered with an injection, usually in the upper arm, or with a nasal spray. Remember, the nasal spray vaccine is indicated only for people aged between 2 and 49, who are not pregnant, and have no chronic health problems, like asthma, diabetes, heart conditions, and kidney failure.

Most people will need only one dose. However, the CDC recommends that children aged nine years or under be given two doses, four weeks apart.

Contraindications

Only a few people cannot receive the 2009 H1N1 vaccine. These include those who previously had

• the paralytic disorder Guillain-Barré Syndrome (GBS); or
• an allergic reaction to the seasonal flu vaccine.

Also, the vaccine cannot be given to people who are allergic to

• eggs and egg-derived products; and/or
• any component of the vaccine.

People with fever, or other illness, may be asked to wait until they recover, before being vaccinated. There are, usually, no contraindications in case of a mild cold.

Swine and seasonal flu vaccines

The swine flu vaccination campaign, which is estimated to take not less than eight weeks to complete, is being undertaken at the same time as the seasonal flu vaccination campaign. This is generating some confusion, particularly among those who need both vaccines, like pregnant women and people with underlying health problems.

According to the CDC, the 2009 H1N1 flu vaccine and the seasonal flu vaccine can be given at the same time, either as two flu shots or one shot and one nasal spray dose. They cannot be given at the same time, if both are in nasal spray form.

Why should you get the vaccine?

Because

• vaccination will protect you from infection, and its serious, potentially fatal complications, like pneumonia; and
• will prevent you from passing it onto your family–your children. So, they will less likely to get ill, too.

And because the more people are vaccinated the less the swine flu will spread. This will reduce the risk of infection for those who cannot receive the vaccine, like babies younger than six months. It will also avoid disruption to hospitals and physician’s offices, allowing doctors and nurses to care for those who become ill.

Justified concerns over availability

The vaccination program is voluntary. So, people will have to make their own decision as to whether they want to be vaccinated. The hope is that most of them will, so as reduce the spread of the virus and to avoid unnecessary deaths.

Some argue this is highly unlikely, because there won’t be enough vaccine for everybody. This may sound like alarmism, but, according to Dr. Anne Schuchat, of the CDC, a shortage of the 2009 H1N1 vaccine is a real possibility.

In a briefing, held October 16, Dr. Schuchat said: “It's very difficult to predict exactly how many doses we'll have in the weeks ahead… some of the manufacturers have let us know that the production of the vaccine is likely to be a bit delayed in terms of the number of doses they were expecting to have out… [so] it doesn't look like we're going to be able to make those estimates that we had projected for the end of this month.”

She added: “We had hoped … we might be around 40 million doses … [now] we think at most it might be about a 10 to 12 million doses fewer than that.”

No shortcut taken

Shortage is not the only factor that could undermine this vaccination campaign. There’s another problem. Recent polls have shown that a large number of people don’t intend to receive the swine flu vaccine. They think it’s too risky.

There are fears that the 2009 H1N1 vaccine may be unsafe because it has been rushed. But, health officials say these worries are unfounded, and assure that the vaccine has undergone all the necessary safety and efficacy tests.

“It's important for people to know that the H1N1 influenza vaccine is being made exactly the same way that seasonal flu vaccines are made,” said Dr. Schuchat. “100 million people get those every year and we believe there's a very strong safety record for them including many pregnant women… and many children…”

“We have [also] increased our safety monitoring efforts… we’re not taking that for granted. No shortcuts are being taken… in the way this vaccine is being produced.”

Side effects are mild

In fact, several clinical trials are currently being carried out to constantly monitor the effects of the 2009 H1N1 vaccine in children and adults. The preliminary results of a study published in the New England Journal of Medicine show no deaths or serious adverse events among individuals aged 18 to 64 years, who received the vaccine. Only mild side effects, mostly tenderness or pain at the site of injection, were reported.

Other data, from the vaccination program that is being conducted in China, show that only 4–out of 39,000–people who received the vaccine experienced side effects. These were minor problems, such as muscle cramps and headache.

What about Guillain-Barré Syndrome?

Probably the biggest worry in terms of side effects is the paralytic disorder Guillain-Barré Syndrome, for which some research suggests a possible association with the H1N1 vaccine.

There are two things to consider in this regard. First, the supposed association between Guillain-Barré Syndrome and the H1N1 vaccine refers to data from studies conducted on the swine flu outbreak of 1976. No flu vaccine has been associated with GBS, in studies, since then.

Second, according to scientists, the risk of developing GBS from the H1N1 vaccine is approximately one case per million people vaccinated. This should be balanced against the number of deaths from flu-related complications, which is 1 in 8,300 each year.

Preservative-free version available

Another concern is the possible link between thimerosal (a mercury-based preservative contained in the 2009 H1N1 vaccine) and autism. Dr. Schuchat said “there’s no scientific basis for those concerns.” However, in order to not deter people from wanting to be vaccinated because of the preservative, the vaccine also comes as a thimerosal-free nasal spray. Thimerosal-free pre-filled single syringes will soon be available.

Adjuvant free

Dr. Schuchat also confirmed that the 2009 H1N1 vaccine does not contain squalene-based adjuvants, or any other adjuvant.

Squalene is a natural oil found in humans, animals and plants. It is used in substances called ‘adjuvants’, which are added to vaccines to increase their efficacy. Squalene has been linked with incurable autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis and lupus.

“None of the [H1N1] vaccine being shipped out has adjuvants,” said Dr. Schuchat, “and we’re not expecting to use it this season.”

The “best protection”

“[This] vaccine is the best protection against this virus,” said Dr. Schuchat. And this is the first time in history that people have a vaccine against a pandemic flu. It just seems irresponsible not to vaccinate and, by doing so, allow the same devastation of past pandemics to occur.

References

Evans D., Cauchemez S., Hayden F.G. “Prepandemic immunization for novel influenza virus, swine flu vaccine, Guillain-Barré syndrome, and the detection of rare severe adverse events,” Journal of Infectious Diseases, August 1, 2009, 200(3):321-8.
Greenberg M.E., Lai M.H., Hartel G.F., Wichems C.H., Gittleson C., Bennett J., Dawson G., Hu W., Leggio C., Washington D., Basser R.L. “Response after one dose of a monovalent influenza A (H1N1) 2009 vaccine – preliminary report,” New England Journal of Medicine, September 10, 2009. DOI: 10.1056/NEJMoa0907413.
Centers for Disease Control and prevention (CDC), H1N1 flu vaccination resources. http://www.cdc.gov/h1n1flu/vaccination. [Accessed 10.18.09]
Centers for Disease Control and prevention (CDC), U.S. Department of Health and Human Services, Press Briefing Transcript, October 16, 2009.
Centers for Disease Control and prevention (CDC), U.S. Department of Health and Human Services, Vaccine information statement – 2009 H1N1 inactivated influenza vaccine, October 2, 2009.
U.K. Department of Health (DH) H1N1 swine flu vaccination program 2009-2010, October 2, 2009.
World Health Organization (WHO), Squalene-based adjuvants in vaccines. www.who.int/vaccine_safety/topics/adjuvants/squalene/questions_and_answers/en/index.html. [Accessed 10.20.09]