The White House coronavirus task force will examine more closely just how much SARS-CoV-2 might be transmitted via aerosols, and not just from droplets, NIAID director Anthony Fauci said Wednesday at an online forum sponsored by Harvard T.H. Chan School of Public Health.

Why it matters: The longer the coronavirus can remain infectiousin the air, the more likely it caninfect people, particularly indoors — leading to the possible need to alter air filtration and circulation within buildings.

Where it stands: The traditional theory, Fauci said, is "if you have a particle that's greater than five micrometers, it's likely going to fall down. If you have one that's less than five micrometers, then you can get an aerosol [of it] floating."

• However, Fauci said virus particle specialists reached out to him to say "you really better take a bigger look at this, because from what we know about particle physics and airflows, there may be droplets that may be much larger than five micrometers that continue to go around."
• Fauci said that to him, "it gives you a greater reason to wear your mask at all times. But, it also tells you that outdoors will likely be much better than indoors."
• "When you are indoors, you've really got to look at what the circulation is and should you be doing things like filtering with HEPA filters. These are things that are unknown now, but that is something we are going to address."

What's next: Fauci says the coronavirus task force will take a closer look at whether or not the virus is aerosolized and already is reaching out to the few Biosafety Level 3 facilities that can test both aerosolization and transmission of infection.

What to watch: Immunity afforded by T-cells, rather than antibodies, is another topic the coronavirus task force will focus upon, Fauci told forum moderator Sanjay Gupta, neurosurgeon and chief medical correspondent for CNN.

• Gupta pointed out research published Tuesday in Science showing evidence of T-cells in blood samples taken in 2015–2018 — before the pandemic — reacting with SARS-CoV-2. That finding supports prior studies that found some T-cell reactivity to SARS-CoV-2 despite no known exposure to the virus.
• People who have been exposed to other coronaviruses (like the common cold) likely develop antibodies that diminish over time. However, the T-cell part of the immune system response has longer term memory and could have some cross-reactivity with this new coronavirus, Fauci said. More research is needed to determine this, he added.
• "[I]t could explain why some people — particularly children who might be closer to the response of the common cold virus — why they may not be getting ill," Fauci said.