VIRUS CASE NUMBERS STEADILY CREEPING UP IN COUNTY

Antiviral drugs, now abundantly available, remain underutilized

A steady increase in the amount of virus detected in wastewater, combined with more than two weeks of evidence that the pandemic is once again growing, suggest that the coronavirus has remained active in the community this spring even as the impact on hospitals so far remains low.

Fortunately, the supply of antiviral drugs has surged to unprecedented levels with nearly 8,000 doses of Pfizer’s Paxlovid now available at pharmacies across the region, according to the federal government’s online COVID-19 therapeutics locator.

At the moment, though, experts say there is a mismatch between supply and demand. Pharmacies must go through the county health department to order these drugs, but so far demand has not been significant.

“(Pharmacies are) not asking for as much as we would expect, because they already have it on the shelf,” said Dr. Eric McDonald, the county’s chief medical officer.

If taken early enough after infection, these drugs can stop the virus from replicating, reducing the chances of severe illness and death by more than 80 percent. As case rates rise, a greater number of residents at risk for serious

COVID-19 consequences should be availing themselves of oral antiviral medications.

Modeling shows that viral activity has been significantly on the rise for weeks.

State estimates of the virus’s effective replication number have exceeded 1 in the state’s composite estimate since April 14, falling from a recent high of 1.26 Friday. The number is a statistical best guess of how many additional infections each new case is generating. Numbers greater than one show a state of exponential growth while those less than one show a shrinking public health threat.

The rise has been borne out in daily new-case totals which, starting this week, the county is only publishing on Mondays and Thursdays.

According to the latest update, 837 new cases were reported to the county Wednesday with all but one day in the past week over 400 cases per day and the total on April 29 nearly reaching 1,000 cases. It’s a significant change over the situation in early April when daily numbers were regularly in the 200s and 300s.

Numbers rising, noted UC San Diego infectious disease modeler Natasha Martin, mean more these days as so many opt for home tests whose results usually are not included in public health department totals.

“In that sense, an increase in reported cases is a big red flag because, even if true case numbers were stable, we might expect to see county numbers decline as a greater fraction of people test at home through antigen testing and don’t report their infections,” Martin said in an email.

More information is starting to appear that helps the public understand just how well antigen tests work in the real world.

San Diego was one of two communities in the nation to participate in an in-depth study of antigen testing conducted by the U.S. Centers for Disease Control and Prevention in early 2021. Published April 29 in the medical journal JAMA Internal Medicine, the paper examines how the effectiveness of antigen testing changes during the course of infection. Researchers followed the results of 552 people living in 151 San Diego and Denver households where at least one person had recently had a lab-confirmed positive coronavirus test, asking all members to take a home antigen test daily for 15 days, recording their symptoms daily.

Researchers found that 225 people in the study tested positive and discovered that the sensitivity of antigen tests peaked four days after symptoms appeared. Antigen tests taken on the same day that symptoms appeared spotted an infection in only about 20 percent of subjects, compared to more than 80 percent for those who instead used lab tests, which use a different technology called polymerase chain reaction. Results were most accurate — with 70 percent to nearly 80 percent of infected patients testing positive — on days two through four after symptoms appeared.

These results, McDonald said, should inform the decisions that patients make after an antigen test. A negative after an exposure or very shortly after symptoms appear very likely is inaccurate.

“A negative home test does not mean that you should throw caution to the wind,” he said.

And understanding and properly using home testing, added Dr. Matt Genovese, a family medicine specialist at Kaiser Permanente San Diego, becomes critical where antiviral drugs such as Paxlovid are concerned. These drugs are only effective, he noted, during the viral replication phase of the infection process, which generally lasts about five days. An antigen test taken too early can end up costing patients valuable time that could have been spent on a drug that could significantly reduce their chances of severe illness.

The best bet, he said, is to simply seek out a lab test as quickly as possible after a symptom of possible coronavirus infection shows up.

“If you know you were exposed and you have symptoms, you really should seek PCR testing if your home test is negative,” Genovese said.

He said the word is clearly starting to get out about antivirals, though several factors have kept the rollout from moving more quickly. These drugs, he noted, do interact with other drugs a patient may already be taking, making doctors less willing to prescribe them for some high-risk patients.

There also is likely a continued misperception that they are still in short supply due to the fact that when they first came available in late 2021, there were only enough doses to help those at the very highest risk. Patients also play a role if they wait too long to let their doctors know that they’re sick, missing that critical five-day window.

“I do think the word is getting out,” Genovese said. “Kaiser Southern California wrote the largest number of Paxlovid prescriptions it ever has on Friday, and we think we’ll top that this week.”

The federal government continues to reserve antiviral drugs for those who are at increased risk of severe infections, but the list of possible risk factors is quite broad. With the drugs now widely available, anyone age 65 and older qualifies, in addition to those with compromised immune systems and those with chronic diseases from diabetes to cirrhosis of the liver. Those with learning and developmental disabilities are also on the list, as are those with heart conditions such as coronary artery disease. Those with body mass indexes of 30 or greater are also on this list, as are those who are physically inactive and current and former smokers. The full list is available at cdc.gov/coronavirus.