A new COVID-19 variant called HV.1 has become the dominant strain in the United States and now accounts for nearly one-third of cases nationwide.
The highly infectious omicron subvariant has been circulating in the U.S. since the summer. In October, HV.1 rapidly gained speed and overtook other variants, including EG.5, aka Eris, to become the most prevalent strain, according to the U.S. Centers for Disease Control and Prevention.
During a two-week period ending on Nov. 11, HV.1 accounted for 29% of new COVID-19 infections in the U.S., per the CDC. After HV.1, the next most common variant was EG.5, which made up about 22% of cases, followed by FL.1.5.1 or “Fornax,” and XBB.1.16 or “Arcturus.” Unlike its predecessors, HV.1 has yet to gain a catchy nickname.
All of the COVID-19 variants that have become dominant in the U.S. over the last year are descendants of omicron, which began circulating in November 2021.
The emergence of HV.1 demonstrates how the SARS-CoV-2 virus, which causes COVID-19, is able to mutate and give rise to new, highly contagious variants.
HV.1's reign comes as the U.S. enters the thick of respiratory virus season and health officials roll out updated COVID-19 vaccines. While the new booster still offers protection against newer variants, very few Americans have gotten the shot so far, TODAY.com previously reported.
Right now, COVID-19 cases and hospitalizations seem to be trending downward following a late summer surge, per CDC data. However, infections are expected to increase again this winter as was the case the past three winter seasons, Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, tells TODAY.com.
As HV.1 continues to spread, many are curious if the new variant is more contagious or severe than previous strains, whether it's causing different symptoms, and when they should get the updated COVID-19 vaccine. Here’s what we know about HV.1 so far.
What is HV.1, the new COVID variant?
HV.1 is part of the omicron family. “You can almost think of HV.1 as a grandchild of omicron,” says Schaffner. HV.1 is a sublineage of omicron XBB.1.9.2 and a direct descendent of EG.5, according to the CDC's SARS-CoV-2 lineage tree.
“The COVID family of viruses likes to mutate. We’ve all learned that by now," says Schaffner. While HV.1 is mutated, it's still very close to the existing omicron subvariants, Schaffner explains.
For the most part, scientists are not concerned about new variants like HV.1, which look very similar to strains we've already seen before, NBC News reported.
However, there are a few highly mutated strains which have set off alarm bells. These include BA.2.86 or Pirola, which has an extra 36 mutations that differentiate it from XBB.1.5., and a newer variant called JN.1, which has one more mutation than Pirola.
Fortunately, neither BA.2.86 nor JN.1 are common in the U.S. right now, according to the CDC — JN.1 is so rare that it makes up fewer than 0.1% of SARS-CoV-2 cases.
As for HV.1, it rapidly gained steam after it was first detected this past summer. In late July, HV.1 accounted for just 0.5% of COVID-19 cases in the U.S., CDC data show. By Sept. 30, HV.1 made up 12.5% of cases, and by November, it was the dominant strain.
Is HV.1 more transmissible?
“One of the characteristics of this entire omicron family is that they are highly transmissible," says Schaffner.
Just like other omicron subvariants, HV.1 is highly transmissible, Dr. Priya Sampathkumar, infectious disease specialist at the Mayo Clinic, tells TODAY.com.
Sometimes, mutations can enable a new variant to spread more effectively or quickly, per the CDC.
Right now, it appears that HV.1 could be better at spreading from person to person than previous strains, NBC News reported. The increased transmissibility of HV.1 likely explains how it became dominant so quickly in the U.S., Schaffner notes.
It also appears that HV.1 could also be slightly better at escaping prior immunity to COVID-19, but not enough to cause alarm, Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, told NBC News.
"The problem is that most people's immunity has faded from past outbreaks and our vaccine uptake is still very low ... so it's too soon to draw any conclusions about HV.1 (evading) immunity from prior infection or vaccination," says Sampathkumar.
Although it is more transmissible, HV.1 does not appear to produce more severe disease or lead to more hospitalizations, Schaffer says.
What remains unclear is whether HV.1 could cause a major uptick in COVID-19 cases. "If there's vast numbers of people getting infected, even if the disease for most people isn't very severe, we will see an uptick in hospitalizations and deaths," says Sampathkumar.
Health officials are monitoring HV.1 closely, but low levels of testing have made it harder to accurately track new variants, experts note.
What are HV.1 symptoms?
The symptoms caused by infection with HV.1 are similar to those caused by recent variants, says Schaffner, which include:
Congestion or stuffiness
Fever or chills
“Congestion, sore throat and dry cough seem to be the three most prominent symptoms right now,” says Schaffner.
Increasingly, doctors report that COVID-19 symptoms appear to follow a pattern of being concentrated in the upper respiratory tract, starting with a sore throat and followed by congestion or a runny nose, NBC news reported.
Coughing isn't typically a primary symptom, but it can persist. "The virus seems to produce a kind of a chronic bronchitis, so that you can have a cough syndrome that lasts beyond the period where you’ve recovered from other symptoms," says Schaffner.
"I haven’t really heard of anything very different or any new symptoms that may raise alarms," says Sampathkumar.
Another trend is that COVID-19 seems to be causing milder illness, likely because people have some prior immunity. “By milder, we mean it doesn’t require hospitalization even though you can feel quite miserable for several days,” says Schaffner.
Do COVID-19 tests detect HV.1?
All COVID-19 tests — including PCR tests performed by a health care provider and rapid at-home antigen tests — will detect HV.1, says Schaffner.
Testing is a crucial tool to protect yourself and others from COVID-19. The symptoms of HV.1 and other COVID-19 variants can look very similar to other viruses, including respiratory syncytial virus (RSV), influenza and rhinovirus, which usually causes the common cold.
There's no way to tell these viruses apart based on symptoms alone, says Sampathkumar.
"The only way to distinguish (COVID-19) from RSV and flu, both of which are now gaining steam, is by testing," says Schaffner.
Experts encourage anyone who has symptoms or has been exposed to get tested, especially those in high-risk groups — people over the age of 65, who are immunocompromised or who have underlying health conditions.
“We have treatments that can prevent more serious disease," says Schaffner, but early detection is key. COVID-19 antivirals such as Paxlovid are effective against HV.1 and other variants, but they work best when within five days of symptom onset, TODAY.com previously reported.
Testing has significantly diminished in the U.S. in the last year, which is concerning, says Schaffner.
When the U.S. federal public health emergency for COVID-19 ended in May, so did the guarantee of free testing for many. Now, the cost of COVID-19 testing will vary depending on your health insurance plan.
However, every American can still order four free at-home COVID-19 tests from the government, which will be delivered by mail via the U.S. Postal Service. To order your free tests, go to COVIDTests.gov.
Uninsured individuals may still be able to access free or low-cost tests through community health centers and participating pharmacies, per the U.S. Department of Health & Human Services.
If you still have a stockpile of tests sitting around, remember to check the expiration date and whether it's been extended by the U.S. Food and Drug Administration.
Does the new COVID-19 vaccine protect against HV.1?
The updated COVID-19 vaccine is recommended by the CDC for everyone ages 6 months and older. It is now widely available at pharmacies, doctor's offices and other locations around the U.S., says Schaffner.
The new boosters have been reformulated to target omicron XBB.1.5, which was the dominant COVID variant for most of 2023. While XBB.1.5 has since been overtaken by HV.1, Eris, Fornax and Arcturus, it is still closely related to these newer strains.
The updated shots seem to be well-matched to the variants currently circulating and making people sick, Andrew Pekosz, Ph.D., virologist at Johns Hopkins University, previously told TODAY.com.
“Laboratory studies indicate that the updated booster will protect against serious disease caused by HV.1,” says Schaffner. Vaccination also significantly lowers the risk of becoming hospitalized or dying, per the CDC.
As of Nov. 13, only 13.9% of adults and 4.9% of children in the U.S. have gotten the new vaccine, according to data from the U.S. Centers for Disease Control and Prevention.
The first phase of the vaccine rollout hit several speed bumps, including supply delays, high demand, cancelled appointments and insurance obstacles. Some parents have been unable to get their kids vaccinated as some pharmacies and pediatrician's offices have struggled to secure enough child-size doses.
Although many of these initial issues have been resolved, says Schaffner, uptake is still slow. "We've underutilized this updated vaccine, and we anticipate that COVID will once again increase even more during the winter season," says Schaffner.
It's not too late to take advantage of the new booster, Schaffner adds, and people should get the shot as soon as they can. While people are getting their COVID-19 vaccine, they should get their seasonal flu shot as well, Sampathkumar adds.
The FDA has authorized three vaccine options for 2023-2024: one mRNA shot each from Moderna and Pfizer, and a protein-based non-mRNA shot from Novavax.
Insurance plans should cover the updated booster, says Schaffner, and those without insurance should still be able to get the shot for free, according to the CDC.
“We’re in a good place because for a considerable time now, we have not had a new variant that causes more severe disease or evades the protection of currently available vaccines,” says Schaffner.
How to protect yourself from HV.1
As the winter and holiday season approaches, it's important to take steps to protect yourself from COVID-19 and prevent transmission to others, especially the most vulnerable. These include:
Staying up to date with COVID-19 vaccines
Getting tested if you have symptoms
Isolating if you are testing positive for COVID-19
Avoiding contact with sick people
Improving ventilation or gathering outdoors
Washing your hands with soap and water frequently
Wearing a mask in crowded, indoor spaces
CORRECTION (Nov. 27, 2023, 10:30 a.m. ET): A previous version of this story incorrectly stated that insurance companies are still required to reimburse the cost of eight at-home COVID-19 tests monthly. When the federal emergency for the pandemic ended in May 2023, insurance companies were no longer required to do so. But some insurers are still reimbursing the cost of tests. Check your plan for more information.
This article was originally published on TODAY.com