The White House’s chief medical advisor Anthony Fauci advised against making the same assumptions about the current monkeypox outbreak that were made during the early days of the HIV/AIDS epidemic.

Fauci and H. Clifford Lane, deputy director for clinical research and special projects at the National Institute of Allergy and Infectious Diseases (NIAID), published a piece in the New England Journal of Medicine on Thursday in which they reflected on the similarities between the monkeypox outbreak and the HIV/AIDS epidemic, which both men spent much of their careers studying.

The two researchers noted the obvious similarities, namely that most monkeypox cases have so far been detected among men who have sex with men. While the main mode of transmission for monkeypox is believed to be through prolonged skin-to-skin contact, they observed that some early data has suggested sexual transmission may play a role in the spread of the virus.

Public health officials have repeatedly stressed that while many monkeypox cases appear to have been transmitted during sexual encounters, the virus itself is not considered to be a sexually transmitted infection.

“Given how little we know about the epidemiologic characteristics of the current outbreak, it is prudent to heed an observation made during the first year of the HIV/AIDS pandemic: ‘… any assumption that it will remain restricted to a particular segment of our society is truly an assumption without a scientific basis,'” Fauci and Lane wrote.

To better understand the virus, the two infectious disease specialists called for further studies and surveys as well as continued surveillance of new cases. According to federal data, over 16,000 U.S. monkeypox cases have been confirmed so far.

In the piece, Lane and Fauci — who is stepping down from his positions in the White House and the NIAID in December — noted there are some characteristics of monkeypox that suggest recent changes that led to the current outbreak, but emphasized that the virus has been known of for decades, with readily available vaccines and treatments.

“Thus, the challenge to the public health and research communities during this time of emergency response is to ensure the efficient and equitable availability and distribution of existing countermeasures to those in need of them while at the same time conducting the rigorous studies needed to define what the clinical efficacy may be, understand any potential safety concerns, and guide proper utilization,” they wrote.