SAN DIEGO (KGTV) -- As vaccinations have accelerated, COVID-19 testing across the country has sharply declined, prompting concern from health experts that undiagnosed cases could contribute to a resurgence.
Nationwide, the average number of tests dropped from a peak of 2 million per day in mid-January to about 1.3 million per day last week.
Some of that reduction is because of falling case numbers and mounting vaccinations, but according to data from Johns Hopkins University, at least 23 states are not testing enough based on positivity rates.
“When you see this reduction in the testing, you kind of get worried because that means there are cases out there that are going unnoticed,” said Dr. Tyler Smith, an epidemiologist and professor at National University.
“When there are cases out there going unnoticed, that means there are more people exposed. And that means there are individuals that are going to pick it up,” he added.
The rapid pace of vaccinations has taken a bite out of case numbers, Dr. Smith said, but it won’t solve the pandemic alone.
This month, British researchers published a study forecasting that even if 85 percent of the UK population got vaccinated, the epidemic would continue to grow if health officials abandoned other control measures. The study underscored the importance of tracing and isolating exposed people, which can only happen with robust testing.
“That has to continue,” Smith said of contact tracing efforts, “and this will continue for years.”
Although the pace of testing has also declined in California, the state’s test positivity rate is the lowest in the country at 1.5 percent, suggesting the state is performing enough tests. According to the World Health Organization, a positivity rate of 5 percent or less is indicative of a healthy testing rate.
But in a half dozen states like Michigan, Idaho and Iowa, test positivity rates are in the double digits.
Experts say there are a confluence of factors that contributed to the testing decline.
Early in the pandemic, testing efforts were concentrated at government-run, mass testing sites, like the one at the Mission Valley stadium in San Diego and Dodger Stadium in Los Angeles.
When vaccines started rolling out, local governments shifted their focus, closing mass testing locations in favor of mass vaccination sites.
Another factor has to do with human behavior, said UC San Diego infectious disease expert Dr. Davey Smith. In many places, there is adequate testing available through private providers. The challenge is encouraging people to utilize it.
“We call it COVID fatigue,” he said. “I'm tired of getting a nose swab stuck in my nose. I'm tired of going in and waiting for a test. The last two or three tests that I did were negative, so this one's likely to be negative too.”
He says people might be more inclined to dismiss mild symptoms at this point in the pandemic, especially if they’ve previously been infected with COVID or vaccinated.
But he says testing remains critical, particularly in our efforts to stamp out variants.