Officially, swine flu has caused the deaths of more than 800 people around the world, with Saudi Arabia and Israel among the latest countries to have reported deaths from the disease.
Overall, more than 134,000 cases of infections have been reported to the World Health Organization, but the figure is likely to understate the actual caseload.
RFE/RL correspondent Antoine Blua asked leading Dutch virologist Albert Osterhaus what swine flu is, how it infects people, and how you can protect yourself against infection.
RFE/RL: Swine flu is a new form of the type of flu virus that normally infects pigs, and also a mixture of other viruses. Is that right?
Albert Osterhaus: The swine flu, or Mexican flu, or new variant H1N1 virus, is an influenza virus that has probably arisen by a mixture of different influenza viruses in swine, has been transmitted to human, and has become able to transmit very efficiently from human to humans.
And since this is a new introduction of a new influenza virus in the human population and this virus transmits easily from human to human, it can cause a worldwide epidemic, or a pandemic outbreak of influenza.
RFE/RL: What are the most vulnerable groups?
Osterhaus: The classical risk group, the elderly, [is] generally not so much at risk because it seems that there is some resistance in that particular population over 65 -- although that's not an absolute resistance.
In addition we have seen that people with underlying disease, people with a not-too-well functioning immune system -- people with asthma, pregnant women, people with obesity -- seem to be more at risk.
What is also interesting is that relatively young people -- from 5 to 35 -- are more susceptible than older people."
Cause Of Infection
RFE/RL: Are people focusing on the wrong thing when they worry about pigs?
Osterhaus: At this moment, the most likely source of infection is human-to-human transmission, although it has been speculated that the virus originates from pigs, and there's some indication there. So, these pigs can become infected, most probably, but people are not being infected by pigs generally speaking.
[And] eating pork is not associated with getting infected with this particular Mexican or swine flu at all.
RFE/RL: When should someone suspect they have become sick with this new virus?
Osterhaus: The symptoms are quite similar to ordinary flu: high fever with respiratory symptoms, a sore throat, chills. And in an uncomplicated form, you would be sick for five, six, seven days, be in bed for that time, and then you would be not feeling too well for another one to two weeks.
If you get the typical [flu] symptoms, if that's in an area where the virus is spreading actively, or after coming from such an area, or after being in touch with somebody who has suffered or is suffering from the disease, you should suspect you have the [swine-flu] symptoms.
Fighting The Flu
RFE/RL: The World Health Organization has declared a global pandemic. It has labeled the new strain "unstoppable" and therefore all countries will need to have access to vaccines. The seasonal flu vaccine being no protection, when can we expect a new vaccine be developed?
Osterhaus: Pharmaceutical companies are working on that. The experience that has been gathered with the avian flu virus [H5N1] is being used to produce vaccines on the basis of the new variant H1N1 virus. And we expect the first vaccine doses to become available by September-October.
RFE/RL: How can people avoid being infected and how can the disease be fought? Can infected people be treated by existing antiflu drugs?
Osterhaus: If you are in an area where the virus is endemic and spreading, it's not always possible to avoid becoming infected. Of course, medical intervention strategies might help.
First of all, it's important to know who is infected and stay away from the infected people. That can only be done at the initial stages.
A second way to combat this disease or to prevent it is to use an antiviral like Tamiflu and Relenza. A strategy would be to wait until you have the very first symptoms and then immediately start the treatment, and then the disease would be very mild [and] short.
But vaccines are eventually, probably, going to be the final answer to the problem.