Swine Flu — Answers to Your Questions

The reporters at our medical unit here at ABC have been in touch with experts all weekend long regarding the Swine Flu outbreak.  Here are some frequently asked questions and answers.

1.     Shouldn’t we be seeing an increase in the total numbers in Mexico, with so many countries now reporting cases?

Both the CDC and the World Health Organization have cautioned journalists today not to make too much out of the numbers because the situation is rapidly changing.  However, some infectious disease experts say they would have expected a spike in Mexico if the disease had big pandemic potential.  Others say the spike could still be coming.

“This virus spreading so rapidly. Very significant development,” said Robert Webster, a world-renown flu expert from St. Jude Children’s Research Hospital.

Ed Hsu from the University of Texas  predicts a rise in cases over the next week followed by a sharp decline thereafter: “Based on the analysis of the SARS data … and our analysis of worldwide H5N1 data, if the trends hold true for H1N1 [swine flu], we will see substantial increase …next week through early May. However, again if the trends hold true, we can also reasonably expect the cases will go down dramatically beginning the week after (i.e., week of 5/3). Note that the rise in cases in next week is normal and expected …Next week will be a critical period to closely watch for case increase.”

But right now the situation is very unclear. “…with all the panic it is very hard to get a handle on whether everybody with a runny nose and fever has swine flu,” said David Freedman of U Alabama.  “Remember that there are only 20 cases or so in Mexico that have unequivocal lab proof of swine flu.”

2.     Should the alert level be raised by WHO? Should it be raised by CDC?

Experts are all over the place on whether the WHO and CDC should be sounding alarm bells.  Some refuse to speculate, others say health officials are taking the right approach given the information in hand, while still others say the threat level should be raised.

3.     Baxter says it is working with the CDC to develop a vaccine in half the time it normally takes. Can you describe how they would do that and if it has been reported before?

Infectious disease experts did not speculate much on which technologies Baxter might use to create a vaccine, should one become necessary.  There are a few possibilities, but perhaps the most likely is a cell-based vaccine that does not use eggs for development.  Because a cell-based vaccine does not require the virus to grow in eggs, it’s expected to be quite a bit faster.  How much faster is unclear since no one has yet to try to mass-produce a cell-based vaccine.  But Baxter has proven the approach can work on a small scale by publishing a paper last year in the New England Journal of Medicine on a vaccine against another flu strain with pandemic potential – the H5N1 virus in Asia.

4.     What does the data show about the effectiveness of masks, such as the ones being handed out in Mexico?

Experts have mixed feelings on the utility of masks to prevent flu.  Some are enthusiastic while others feel the benefits are unproven.  A Cochrane 2009 review of studies on the subject found “limited evidence” that the (more uncomfortable and expensive) N95 masks were superior to simple ones.   Much of influenza transmission is believed to occur through touching in any case, so frequent hand washing is really a major priority.

Click here for more on how to prevent and contain the swine flu.