Can We Get to Herd Immunity by April? Most Experts Skeptical – Healthline
- Many factors can influence how soon the United States will reach herd immunity for COVID-19, but many health experts expect the end of the pandemic is in sight.
- It’s theoretically possible the United States could reach herd immunity by the end of spring.
- But new SARS-CoV-2 variants and spotty vaccine availability make this unlikely, according to some experts.
Also known as community immunity, this is the point at which enough people are immune to a virus — through vaccination or natural immunity — that the virus no longer easily spreads through a population.
That means a majority of people would need immunity to block the spread of the virus through a community.
Herd immunity isn’t just an abstract calculation made by virologists and epidemiologists. It has implications for how soon public health restrictions such as physical distancing and mask mandates can be safely lifted.
To put it another way: How soon will life return to “normal”?
Many health experts are optimistic that the end of the pandemic in the United States is in sight, although it’s not clear what the transition to “normal” will look like.
Some experts are more optimistic than others.
“I expect Covid will be mostly gone by April, allowing Americans to resume normal life,” wrote Dr. Marty Makary, a surgeon and a professor at the Johns Hopkins School of Medicine and Bloomberg School of Public Health, in a commentary in The Wall Street Journal.
He points to the sharp drop in COVID-19 cases in recent weeks as a sign that parts of the country are nearing, or have reached, herd immunity.
This decline in cases is “in large part because natural immunity from prior infection is far more common than can be measured by testing,” he wrote.
That would mean that about 55 percent of Americans have natural immunity.
If you combine this with the 150 million people that Makary estimates will be vaccinated by the end of March, that brings the country close to the herd immunity threshold.
Not every health expert, though, agrees that the country will be open for business by April.
Topol has several concerns about the commentary, including Makary’s estimate of how many people have natural immunity due to past SARS-CoV-2 infection.
Other research suggests that the level of natural immunity in the United States may be lower than Makary’s calculation.
Topol also doubts that the United States will hit 150 million vaccinations by March.
If you take the Columbia University researchers’ estimate of the extent of natural immunity in the country, millions of people are still susceptible to this new coronavirus.
If public health measures are relaxed too soon — before enough people can be vaccinated — the country could see another spike in cases, hospitalizations, and deaths.
He said his projection is based on several new developments over the past month.
One is the high number of people who won’t be vaccinated anytime soon — either the third of Americans who say they won’t get vaccinated, or children under age 16 who aren’t yet eligible for a vaccine.
Gao said another development that could affect herd immunity is new SARS-CoV-2 variants that may lower the effectiveness of COVID-19 vaccines.
If the vaccines offer less protection, more people will need to be vaccinated in order for the country to reach herd immunity.
Topol is also concerned about the impact of more transmissible variants.
“[Makary] turns a blind eye to variants,” he wrote on Twitter, “particularly B.1.1.7, which has accounted for peak pandemic surges, hospitalization, and deaths in Israel, UK, Ireland and Portugal, and [is] now seeded throughout the US.”
Other factors can also influence how long it will take the country to reach herd immunity, such as the duration of immunity — from the vaccine or after infection — and whether the vaccine prevents people from transmitting the virus to others.
Scientists are still studying both of these questions.
Christina Ramirez, PhD, a professor of biostatistics at the UCLA Fielding School of Public Health, said until we know the answer to these questions, we’ll have to keep some public health measures in place.
The New York Times and The Washington Post created interactive models that show how different factors can affect the path toward herd immunity — and the number of people who could die from COVID-19 under different scenarios.
These models highlight what public health officials have long been saying about COVID-19: The safest path to herd immunity is through vaccination.
Although Gao’s model has contributed to the herd immunity discussions, he cautions against focusing too much on reaching this threshold.
Ramirez agrees. She points out that the COVID-19 vaccines approved so far have all been very effective in reducing severe COVID-19 and deaths.
“Even with the variants, data shows that the new vaccines really work at reducing hospitalizations and deaths,” she said. “Variant or no variant, if you are at risk [for COVID-19], you should get the vaccine and not wait for herd immunity to protect you.”
- ^ Share on Pinterest (www.pinterest.com)
- ^ plummet (twitter.com)
- ^ 1.7 million a day (www.axios.com)
- ^ 70 to 90 percent (www.nytimes.com)
- ^ Dr. Marty Makary (www.hopkinsmedicine.org)
- ^ The Wall Street Journal (www.wsj.com)
- ^ 28 million confirmed cases (coronavirus.jhu.edu)
- ^ Dr. Anthony Fauci (www.niaid.nih.gov)
- ^ Newsweek (www.newsweek.com)
- ^ Dr. Eric Topol (www.scripps.org)
- ^ wrote (twitter.com)
- ^ 83.1 million people (www.cdc.gov)
- ^ 36 percent (www.npr.org)
- ^ upped the goal to 150 million (www.nbcnews.com)
- ^ analysis of CDC vaccination data (www.nbcnews.com)
- ^ 500,000 people (coronavirus.jhu.edu)
- ^ Youyang Gu (www.linkedin.com)
- ^ covid19-projections.com (covid19-projections.com)
- ^ wrote (twitter.com)
- ^ third of Americans (www.vox.com)
- ^ children under age 16 (www.nytimes.com)
- ^ reduce protective antibodies (www.reuters.com)
- ^ Christina Ramirez (ph.ucla.edu)
- ^ The New York Times (www.nytimes.com)
- ^ The Washington Post (www.washingtonpost.com)
- ^ COVID long haulers (www.npr.org)
- ^ wrote (twitter.com)