Catching a viral tiger by the tail

Three times this century a coronavirus has jumped the species barrier to infect human populations. Each instance has caught the global public health community off guard — including now.

Never has a family of pathogens been as puzzling as coronaviruses, which historically have caused common cold-like illnesses. For reasons that escape scientific explanation, coronaviruses have emerged roughly once each decade in this century in a deadly form.

In 2002, SARS became the first new respiratory disease linked to a coronavirus that had recently jumped from an animal source. In 2012, MERS became the second. Now, the new coronavirus called COVID-19, which causes a respiratory infection, has burst explosively into the human population. Because the virus is new to humans, no one has immunity to it. A vaccine to prevent infection is at least a year away, and a medication to mitigate its impact has yet to be found. Passed through endless chains of coughing and close contact, the virus is relentlessly circling the globe.

A key question facing scientists here and abroad is whether they’ve learned enough to beat back a menace that’s stalking every continent, except Antarctica. Or, have they learned so little that another coronavirus will take the world by surprise in a few years?

Many who are trying to catch a viral tiger by the tail say more was learned about the new coronavirus in its first eight weeks of circulation than was learned about SARS in eight months.

“This is unprecedented to have the virus identified and its sequence shared,” said Dr. Maria Van Kerkhove, referring to the pathogen’s complete genetic blueprint and the dissemination of that data to researchers worldwide. Van Kerkhove, who heads the World Health Organization’s emerging diseases division, added that investigators are studying myriad molecular details about the microbe to discern similarities and differences with its cousin coronaviruses.

In Manhattan, Dr. Florian Krammer, a virologist at Mount Sinai’s Icahn School of Medicine, is among an elite cadre of scientists trying to tease secrets from the pandemic in real time — as it spreads.

The virus itself is technically known as SARS-CoV2. As with SARS and MERS, the new coronavirus attacks the lungs. But there are features that make it unique. It spreads more easily than the other two. The novel coronavirus is what some experts call “a super spreader.”

“While there were some super-spreader events [with SARS], it didn’t transmit as easily, and did so only if the person was symptomatic. SARS-CoV2 has a reproductive number of two to three, which is higher than the influenza virus,” Krammer said of an arcane mathematical construct known as R0 (pronounced R-naught). It allows scientists to calculate the contagiousness of an infectious disease. A reproductive number of two to three means each infected person can spread the virus to two to three people.

The R0 for seasonal flu, which is quite contagious, is around 1.3. Measles has a high R0, in the range of 12 to 18, which means one person with measles can infect 12 to 18 people. A lawyer who lives in Westchester County is believed to have spread SARS-CoV2 to more than 50 people, many of whom were in close contact with him at a New Rochelle synagogue, according to state health officials.

Krammer, meanwhile, is beginning a surveillance project that will allow him and his team to determine where and how pervasively the new coronavirus is spreading. The research can provide a region-by-region depiction revealing where the virus is most — and least — prevalent.

He will collect serum samples nationwide. Serum — blood plasma — is full of proteins. Antibodies are proteins that are abundantly represented in serum samples. They’re produced in response to infectious agents and Krammer will isolate those bearing a unique biological signature.

His search may soon provide a telltale sign of where the pathogen has most expansively infiltrated the population. 

Delthia Ricks is a science journalist and former Newsday health writer.