For the last decade China has maintained a ban on people with HIV/AIDS from entering the country. But the country has revoked the ban after receiving criticism following the barring of an Australian writer who declared he was HIV-positive.

China's regulation formally banned foreigners with "psychiatric illness, leprosy, AIDS, sexually-transmitted diseases, active pulmonary tuberculosis or other infectious diseases." The State Council amended the regulation on Tuesday removing the ban on people who have developed AIDS or are infected with the HIV retrovirus.

The ban still bars foreigners "with serious psychiatric illness, infectious pulmonary tuberculosis or other infectious diseases that may constitute a major threat to public health."

By Julie Stachowiak, PhD
Multiple Sclerosis Guide; Guest blogger

After all that uproar when the vaccine wasn't getting here quickly enough and all that persuasion and urging once it was here, the numbers of people vaccinated against H1N1 in the U.S. should be pretty high. The Centers for Disease Control and Prevention has released a report that tells us the estimated number of American citizens who were vaccinated.

At first blink, it sounds huge (and it is, don't get me wrong) when we consider that 61 million Americans have received the H1N1 vaccine since the fall of 2009. However, put another way, that works out to only 20% - 1 out of every 5 Americans have been vaccinated. I dunno, it just doesn't sound that good.

However, there are other ways to look at it that sound more impressive and hopeful:

1) The CDC says that the people at the very highest risk were the most likely to be vaccinated.

2) The estimated number of people who actually caught H1N1 and got sick from it is 50 million, so the public health people are still 10 million in the lead.

You know what? It's not too late. As a matter of fact, now is a great time to get vaccinated if you (or your kids) are in the 80% who have not gotten your vaccine. Unless you were CONFIRMED by a lab to have H1N1, go get your vaccine. Help yourself (in case another wave of H1N1 infections is coming) and help the statistics. It's just a good idea.

By Julie Stachowiak, PhD
Multiple Sclerosis Guide; Guest blogger

A Reuters article says that the European Center for Disease Control and Prevention (ECDC) is warning that the fact that new cases of H1N1 swine flu are lessening could mean that other flu viruses will start showing up.

Experts say that historically after influenza pandemics, there tend to be new unknown flu viruses that start circulating. They also point out that the pandemic influenza viruses have historically come back after an apparent decline to infect lots more people.

What does this all mean? A couple of things:

• People should go ahead and get the H1N1 vaccine if they haven't done so yet. It should be easy to find these days and most places have lifted any restriction (such as being age 65 and older), so that anyone can get vaccinated.
• If your child only got one dose, they should get their second dose.
• If you haven't gotten your seasonal flu vaccine, get that one, too.
• Continue to follow all of the common-sense cold and flu season precautions, such as staying home if you are sick, washing your hands often and coughing into your elbow.

By Julie Stachowiak, PhD
Multiple Sclerosis Guide; Guest blogger

It looks like some regions are becoming immune to widespread outbreaks of H1N1 swine flu, as they have developed immunity from previous waves of exposure.

"Herd immunity" is a term that describes a community being immune to (not able to catch) a certain disease. This immunity can be conferred either from exposure, meaning that people had the disease and recovered, or vaccination. It does NOT mean that no one in the community can get the disease, it just means that there will not be a large outbreak and that individual infection is therefore less likely.

Herd immunity is an interesting concept, as different diseases require different levels of immunity to protect the community, based on the transmissibility of the virus or bacteria. For instance, measles is one of the most infectious, easily transmitted viruses in people. To achieve herd immunity against measles, between 90 and 94% of the population must have been vaccinated. However, for smallpox, the immunity levels were between 80 and 85%, which is one reason that it was possible to eradicate that disease.

Few experts have tackled the idea of herd immunity to a pandemic flu like H1N1, as it was such a rapid wave and there are many unknowns. True herd immunity seems a little less likely than the fact that these types of viruses usually just "peter out" and move along. However, there is evidence that there has been enough exposure in some southern hemisphere countries that there is no longer widespread infection, but isolated cases of H1N1 occurring, even though the virus is still present.

If you are intrigued with the idea of herd immunity and H1N1, see what you can make of this article, which mentions some interesting assumptions and some difficulties in modeling pandemic influenza: Pandemic influenza dynamics and the breakdown of herd immunity