New CDC guidance proposes taking a common drug after unprotected sex to reduce the risk of an STD as US sees explosion of infections

Taking a common antibiotic within 72 hours of having unprotected sex could lower the risk of sexually transmitted infections (STIs), especially among the LGBTQ+ community. 

On Monday, the Centers for Disease Control and Prevention (CDC) announced it will seek input from the general public on its proposal to offer the inexpensive antibiotic doxycycline as part of a regimen called doxy-PEP to gay men, men who have sex with men and transgender women who have unprotected sex. 

The agency believes the antibiotic could potentially prevent 40 percent of STIs, such as chlamydia, gonorrhea, and syphilis, which have exploded into an epidemic across the US.  

Dr Jonathan Mermin, director of the CDC’s National Center for HIV, Viral Hepatitis, STD, and TB Prevention (NCHHSTP), said: ‘Doxy PEP is moving STI prevention efforts into the 21st century. We need game-changing innovations to turn the STI epidemic around, and this is a major step in the right direction.’

The agency recommends one 200 mg dose of the medication be taken after unprotected sex and it will seek public comment on its proposal until November 16.

Doxy-PEP is only meant to lower STI risk, and the traditional morning-after pill, Plan B, should still be taken within 72 hours of unprotected sex to prevent unwanted pregnancy.

A person may be at risk for an STI if they have unprotected sex with someone who already has an infection. 

Earlier this year, the CDC warned the US is in the midst of an ‘STI epidemic’ that shows ‘no signs of slowing.’

The most recent CDC figures show there were 176,713 syphilis cases in 2021, the highest since 1950 and up a third from 2020.

The report also found a surge in congenital syphilis, which occurs when a baby is born with the infection after catching it from the mother during pregnancy.

Cases of this disease rose by 32 percent from 2,148 in 2020 to more than 2,800 in 2021. This resulted in 220 stillbirths and infant deaths in 2021, the CDC said.

Cases of gonorrhea also increased, rising nearly five percent from 677,769 cases in 2020 to more than 710,000 in 2021, the highest yearly total in four years.

Cases of chlamydia, the most common STI in the US, saw an increase from 1.58 million cases in 2020, to 1.64 million in 2021.

Despite this roughly four percent increase, total yearly cases of chlamydia have declined since 2019, when more than 1.8 million cases were reported. This could be due to Covid social distancing and less testing being performed during the pandemic.

Doxycycline is an inexpensive antibiotic that has been sold in the US for more than 50 years. It’s usually used to treat bacterial infections, such as urinary tract infections and respiratory tract infections, as well as skin conditions like rosacea, which causes red skin and a rash.

However, research shows it could now have promise in reducing the risk of STIs. 

A study in the New England Journal of Medicine, funded by the National Institutes of Health (NIH), involved 501 gay men, bisexual men and transgender women in Seattle and San Francisco with a history of STD infections. The participants each took one 200 mg doxycycline pill within 72 hours of unprotected sex.

Participants who took the pills were about 90 percent less likely to get chlamydia, 80 percent less likely to get syphilis and more than 50 percent less likely to get gonorrhea compared with people who did not take the medication after sex.

Doctors at the University of California, San Francisco and the University of Washington said: ‘The combined incidence of gonorrhea, chlamydia, and syphilis was lower by two-thirds with doxycycline postexposure prophylaxis than with standard care, a finding that supports its use among [men who have sex with men] with recent bacterial STIs.’

There is less evidence suggesting doxy-PEP is effective in cisgender and heterosexual men and women. However, Dr Mermin said this may change as more research is done.

Citing continuous study in this field, the San Francisco Department of Public Health endorsed doxycycline’s use as a prophylactic in October last year.

The department said: ‘Doxy-PEP is the first biomedical prevention tool that has been shown to be effective and well-tolerated, community awareness is growing, and many providers in SF are already prescribing doxy-PEP to their patients at risk for STIs.’

State statistics from the CDC found that Mississippi and Louisiana have the highest rates of sexually transmitted diseases (STDs) in the US.   

In 2021, the most recent data available, Mississippi topped the list for highest gonorrhea rates in the country, with 427.7 infections per 100,000 people.

Cases of chlamydia, a bacterial infection, were also high at 750 per 100,000. And the cumulative number of syphilis rates that year hit 88.3 per 100,000. 

After Mississippi, the state with the second-highest STD rate was Louisiana. The chlamydia rate in that state was 730.1 per 100,000, while the gonorrhea rate stood at 354.5 per 100,000 residents.

Alaska had the third most STD rates overall, but according to the state’s Department of Health and Social Services, rates of gonorrhea and syphilis have been climbing there for years. 

And in 2021, state health officials counted 447 cases of syphilis, a 24 percent increase over the 2020 total.

The likely contributors include a relatively young population – which makes up over 50 percent of all STD cases in the US. Much of Alaska is also remote, which limits the availability of healthcare, and the public health infrastructure is severely lacking.

After Alaska came South Carolina, which recorded 1,052 STDs per capita in 2021. It recorded the fourth-highest rates of chlamydia, with 703 cases per capita. 

The state had the lowest rates of syphilis on the list, with 40.1 cases per capita. 

In South Dakota, which rounded out the top five states, there is limited access to healthcare in rural and Tribal lands. There, syphilis has exploded by more than 1,800 percent, from 41 cases in 2016 to 785 in 2021.

When the CDC will formally recommend doxycycline as a de facto morning-after pill remains to be seen, but officials will have many factors to consider before then, such as the drug’s adverse health risks.

For instance, when combined with the blood thinner warfarin to treat or prevent blood clots, doxycycline can thin out blood further, raising a person’s risk of severe bleeding and bruising. 

Other medications, including over-the-counter antacids and some barbiturates, sedative medications usually used to treat seizures and insomnia, render the medication less effective.

Doxycycline can also cause nausea and vomiting, bloating, dizziness, chills, constipation, and, in more severe cases, rashes, swelling and hives, and blurred vision.