Anyone who has been following the HIV/AIDS crisis from its inception in 1981 has witnessed a medical roller-coaster ride that is unprecedented. HIV infection was a sure killer until 1996, when the long-anticipated AIDS cocktails finally started appearing on the market, and for the first time ever the number of annual deaths in the United States decreased. (Just an aside: There are those who still maintain that the bulk of the research responsible for this advance, and future ones, came from the NIH and that the pharmaceutical industry did little more than manufacture and sell the new AIDS drugs. They have absolutely no idea what they are talking about, and could not be more wrong).

But now, there's better news, astounding really. A new paper in the New England Journal of Medicine says that Truvada, the most effective HIV drug, can now even be used as a "morning after" pill to stop the spread of the virus. The authors say it's as effective as condom use.

This is amazing. Over the last two decades medicines became more effective, so instead of people having to take 30 pills per day, that number was reduced to one or two, with a corresponding reduction in side effects. The projected lifespan for people who were HIV+ began to approach that of uninfected people. By 2011, it became evident that the drugs, primarily Truvada—a two-drug combination pill, could not only restore the immune function of people with HIV, but also reduced the virus levels in the blood so much that they couldn't even be measured.

This resulted in perhaps the single biggest surprise in the 34 years since the virus was discovered: at such low viral levels, it was much more difficult to infect others, and the drugs were so good that they protected HIV-negative people against becoming infected. For the first time, prophylaxis (PrEP) became feasible, but it had limitations. When patient compliance was poor, the level of protection was in the 40 percent range.

Compare that to when compliance was perfect, as shown in a recent clinical trial in San Francisco, protection was 100 percent, regardless of condom use, something I wrote about this past September. In the NEJM study, of the 400 uninfected men who were followed for a time period ranging from 5-20 months, there were 14 infections in the placebo group, but only two in the group that took a double dose of Truvada both before and after unprotected anal sex. There are consequences that result from this new protocol, both positive and negative:

Patient compliance will probably be higher, since men will not have to remember to take their prophylactic medicine every day.

Although Truvada is generally well tolerated, it, like every other drug, does have side effects, mainly gastrointestinal, as well as kidney toxicity. Taking the drug sporadically rather than chronically will surely mitigate these effects.

But, although the transmission of HIV was greatly reduced, the rate of other sexually transmitted diseases went through the roof due to reduction in condom use. There is only so much that a drug can do.

Whether the "morning after" method becomes the treatment of choice remains to be seen, but it is certainly reasonable to believe that it has enough of a benefit to replace the use of chronic prophylaxis therapy. Perhaps as likely is that another "surprise" will appear that will replace both methods. Twenty years ago, no one could have imagined any of this.