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(Carolyn Kaster)
(Carolyn Kaster)

The H1N1 question

Is the flu virus mutating dangerously? Add to ...

Despite a huge amount of information about the H1N1 virus, Canadians still have questions about diagnosis, treatment and how to best respond.

Join André Picard, The Globe and Mail's public health reporter, as he answers questions from readers about the pandemic.

L eave your questions here using the Globe's comment function.

For more answers, see the Globe's previous Q&A's on the virus , the vaccine and parents' questions .

Wednesday, Nov. 25

Q - I saw a story that said the H1N1 was mutating. Does that mean that drugs and the vaccine won't work any more and the flu will be more deadly?

A: There are a couple of issues here.

First, there have been a number of stories about H1N1 developing resistance to Tamiflu, an antiviral drug. This resistance can occur when the drug is misused - when patients don't take the full course of treatment (with Tamiflu that is twice daily for five days.) These resistant strains can spread, making influenza more difficult to treat, but the vaccine still works to protect you against infection.

The Norwegian Institute of Public Health announced last week that it has identified a "potentially significant mutation" in three patients, and that generated a lot of media attention. According to the World Health Organization, the same mutation has been found in China, Japan, Brazil, Ukraine, Mexico and the U.S.

Influenza viruses mutate frequently. That's why you need a flu shot every year - to protect against new strains. During flu season, sporadic cases are expected and not worrisome unless the mutated virus starts spreading person-to-person. So far, there is no evidence that has occurred. So there is no concern about the vaccine not working, at least in the immediate future.

Mutated flu viruses are not necessarily more deadly. In fact, they are often variations (or cousins if you will) of earlier flu viruses so many people can have partial immunity. We have seen this phenomenon with H1N1: Even though it is a novel strain - and thus was believed to have the potential to infect everyone - most people born prior to 1957 have partial immunity. Why? Because, between 1918 and 1957 many strains of H1N1 flu viruses circulated so people developed immunity.

While there is no doubt that H1N1 will mutate, the concern of public health officials is when and how. A major mutation that created a new strain of influenza that spread person-to-person would render the vaccine ineffective but that doesn't seem too likely as H1N1 activity peaks.

The nightmare scenario would be H1N1 (swine flu) hooking up with H5N1, a bird flu that sparked pandemic fears a few years back and which continues to be quite deadly. If those two flu viruses were to swap genetic codes it could create a superbug. Earlier today, a researcher told Reuters news agency that is a distinct possibility because, in China, both viruses are circulating.

"China, as you know, is different from other countries. Inside China, H5N1 has been existing for some time, so if there is really a re-assortment between H1N1 and H5N1, it will be a disaster," said Dr. Zhong Nanshan, director of the Guangzhou Institute of Respiratory Diseases in China's southern Guangdong province.

Friday, Nov. 20

Q: Months ago there were stories about the global pandemic of swine flu. Now all we read about is the flu in Canada. What's going on in the rest of the world?

A: According to the World Health Organization, H1N1 influenza has been reported in 206 countries and overseas territories. There have been 6,770 laboratory-confirmed deaths. The WHO has recorded more than 525,000 cases of H1N1 worldwide but notes that many countries have stopped counting individual cases. (In Canada alone, for example, an estimated 3.5 million people have been infected with the flu.)

In North America, there is active and geographically widespread disease. The flu continues to spread in Northern and Eastern Europe, particularly in parts of the former Soviet Union. Influenza seems to have peaked in Western Europe, such as in the United Kingdom. In Central and Western Asia, flu activity is waning but there are still sporadic outbreaks, such as in Afghanistan and Israel. In East Asia, H1N1 activity continues but is not particularly intense, with the exception of Mongolia. In China and South East Asia there are only small numbers of H1N1 cases and seasonal influenza (H3N2 in particular) is spreading. In the southern hemisphere, where it is no longer flu season, the spread of H1N1 has slowed considerably, with the exception of Peru and Colombia. Transmission of H1N1 has declined sharply all over southeast Asia, with the exception of Sri Lanka. In Africa, there is little flu activity; there have been twice as many H1N1 deaths in Canada is in all of Africa.

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