Why is the current flu shot containing H1N1 ineffective on the current Swine Flu?

Answer 1

The influenza that is currently creating an epidemic and that has been being called the "2009 Swine Flu" is a Type A H1N1 virus, but it is not the only one that is scientifically identified this way. This particular virus has mutated from the H1N1 virus that was a pig virus and not really a human virus. That is why the World Health Organization has named this one "Novel H1N1". Because it contains genetic material from all three: swine flu viruses, avian (bird) flu viruses, and human viruses, therefore the previous H1N1 vaccine would not be effective on this virus that has changed.

Viruses have a protein coat on the outside of their structure called a capsid. There are specific shapes on viruses that physically make them able to latch on to receptor cells in the host animal. This is what keeps most animal viruses from crossing to humans because the receptors cells are shaped so differently and what fits in the other animals' receptors won't fit in human cell receptors. These shapes are some of the features that viruses change when they mutate. The novel H1N1 is different and can fit into human receptors.

The current H1N1 vaccines available are for the pigs to take and are for the strain of H1N1 that pigs have been getting for years, or they are for the seasonal flu strains that humans get that also share the H1N1 features but are not the same as the A-H1N1/09 "Novel" Swine Flu.

The vaccines for the older strains of H1N1 for people and for pigs are not really the best kinds of vaccines (those are still in development), the ones currently available are made from dead viruses and are less effective. FDA hasn't approved live virus vaccines for use for those types of H1N1 flu strains in people yet until more trials, except in very specific situations. Human vaccines for the older swine flu are in development and may be available for workers at hog production facilities only.

The vaccine specifically for the 2009 Pandemic Swine Flu (A-H1N1/09) is due to be released in mid October 2009 and will provide the protection for this Novel Influenza after a loading shot followed in three weeks by a second shot, then a few weeks after the second shot, immunity from this new strain is expected. There will also be a nasal spray available for specific age groups, ask your care professional which type will be right for you and if you are in any of the risk groups.