Friendly Chain Growler — Update

Cherise Rohr-Allegrini, PhD, MPH
4 min readMay 17, 2020


It’s not even been a week since I wrote about the Friendly Chain Growler outbreak but the spread has gone trans-continental and must be documented. A nearly identical illness has popped up in New Hampshire.

Is this a unique virus? Is it a new strain of the same Growler Virus? According to one quasi-epidemiologist who has been tracking this from the start (and who may or may not be the G0/Index Case), “Clearly, it is part of the #CommunityGrowlerSpread virus family but would the #ThrowbackChainGrowler be considered novel?”

Upon studying this New Hampshire version of the illness, scientists think the Throwback Chain Growler virus comes from the same family (Communitiviridae) and genus (Beervirus) as the Friendly Chain Growler Virus.

Both viruses have the same morphology: the amber growler jug.

They also appear to have the same route of transmission: a growler filled with delicious beer from a local brewery or ice house is dropped off on a friend’s porch.

We know the Friendly Chain Growler Virus found its way up I-10 past 1604 recently, but how did the Friendly Chain Growler Virus jump from Texas to New Hampshire?

As there has been no recent direct contact between this New Hampshire host and the San Antonio host, except Facebook, epidemiologists have been scratching their heads — could this be from the same source? Could it be entirely new and have risen independently? The genetic code is very similar and even includes a direct reference #CommunityGrowlerSpread in the code.

Alas, new studies suggest Communitiviridae Beervirus may include a subgenus researchers have tentatively named Southtown Beer Virus. They have traced the origins of both viruses to the wet markets of Southtown, a place well- known for its many vibrant wet markets, especially on First Friday.

Some wet markets in Southtown. Even the author visits the wet markets (and is unsure of the identity of the other person in this photo. Oops)

Based on this information, they believe Southtown Beer Virus is actually an old virus, around since the time the New Hampshire G0 (NH’s Index Case), lived in Southtown. The evidence suggests that NH-G0 had been infected with the Southtown Beer Virus in Texas but it has been dormant in the cold New Hampshire climate. In 2020, however, it re-emerged simultaneously in both states, with each virus having some novel characteristics. The result is that there are two individual, but related viruses, Friendly Chain Growler Virus (FCGV) and Throwback Chain Growler Virus (TCGV). These likely both originated from the Southtown Beer Virus (SBV).

Scientists don’t yet know if the survival of FCGV(TX) and TCGV(NH) on porches is the same. The hot climate in Texas may mean that FCGV(TX) must be drunk immediately to induce infection. It’s possible that the current cooler climate in New Hampshire means TCGV(NH) can survive longer on porches.

As TCGV appears to act similarly to FCGV, we can expect to see a similarly high R0. It is also highly likely that both viruses will show resistance to containment. But we won’t really know until we fully study it.

This will require an army of contact tracers in both locations and a reliance on infected individuals to share truthful information. Of course, if one delivers growlers to a lawn party (appropriately physically distant) and reports “I don’t know their names,” this may prove difficult for tracers.

Rumor has it that even the local mayor visits the wet markets, but has not yet shown any signs of infection.

note: The science is evolving and will be updated as we learn more. Though historically, scientists often named viruses after the location in which they were discovered, for most of the past 15 years or so we name viruses based on the disease they cause. “Drunk Neighbor Virus” didn’t go over well. But we’ve learned that Southtown and The Friendly Spot like the name and we’ll presume Throwback Brewing would be on board, but be prepared for changing nomenclature.



Cherise Rohr-Allegrini, PhD, MPH

Dr. Rohr-Allegrini is an epidemiologist and tropical disease scientist currently working to prevent diseases through immunizations.