UCSF doctor says you may get false negatives on 1st day of testing for omicron

In addition, he says there's a 20% chance you're still infectious 5 days after contracting COVID.
SAN FRANCISCO (KGO) -- Amid the omicron-led coronavirus surge, UCSF Chair of the Department of Medicine, Dr. Bob Wachter, joined ABC7 News on our 3 p.m. program "Getting Answers," to discuss issues related to hospitals, schools and more.

Testing is a common thread in all of these topics, as there is still uncertainty about the accuracy of at-home COVID-19 tests and CDC recommendations.

The CDC recently released new guidelines Dr. Wachter says are "tricky," and don't "make a lot of sense."



He uses his own son as an example.

His son recently tested positive for coronavirus, but not right away. Despite "absolutely having symptoms," his son tested negative on day one.

RELATED: Officials consider reducing COVID isolation period for fully vaccinated

This is something Dr. Wachter says has been a trend with the omicron variant - People are getting false negatives in the early stages of infection.

This is where the trickiness of the CDC guidelines comes in.

The CDC says that people, who don't have a fever and aren't showing symptoms, can return to work after five days of testing positive, even without taking a second test.

RELATED: CDC tries to clarify COVID guidelines on isolation, negative tests after pushback

Dr. Wachter is skeptical about this, explaining at day five, "there's about a 20-percent chance that you're still infectious."

His son retested on day five and was positive. For the second test, Dr. Wachter used a different technique, based on new data.

Should you swab your throat in addition to your nose while performing an at-home COVID test?



That data suggests tests may be more accurate if you swab your throat and nose, instead of just the nose.

However, doing so on your own with an at-home test is not advised. Leave this technique to the certified medical professionals.

"I don't think we know enough yet to say that everybody should do that," Dr. Wachter said.

He assures that the at-home tests are still 95-percent sensitive in detecting omicron, even without the throat swab.

What if you don't have access to a COVID test when you need it?



Acknowledging that not everyone has access to a coronavirus test right when they need it, he shared some advice - if you don't have access to a test, and it's not absolutely necessary for you to return to work, you should "stay out a couple more days, and maybe even the full ten days," he said.

"But I think at least seven days seems like a reasonable balancing point."

He says without a test, wearing a mask becomes even more crucial.

VIDEO: Evidence emerging that cloth masks are not as effective as surgical masks against COVID
EMBED More News Videos

Kristin Thorne has the latest on mask effectiveness and what experts are recommending.



"If you're wearing a really good mask and you're wearing it religiously, like an N95 and you're wearing it religiously, your risk to other people is very, very low," Dr. Wachter explained.

"I don't believe that this is our major threat right now - people on day six after an infection, if they are wearing a good mask."

If you do have access to a test, he advises to take it and if the results are positive, you should assume you are still infectious.

Coronavirus and healthcare workers



The CDC says healthcare workers who test positive but are asymptomatic, can now go back to work right away without having to quarantine.

This comes as California and the Bay Area are experiencing staffing shortages with nurses and other essential workers.

But still, is returning right away the right call?

"It's a really hard call. There's no right answer," Dr. Wachter says, it is "balancing two tough choices."

On one hand, a healthcare worker could still be infectious as they return to care for other people who are sick. On the other hand, there's the possibility of not having enough staff to care for patients, which is also a "dangerous" option, he explained.

VIDEO: South Bay hospitals work to cope with quarantine-related staffing issues
EMBED More News Videos

A South Bay doctor explains how hospitals are managing staffing shortages amid the latest omicron-fueled COVID surge.



He says the silver lining here, is that most, if not all, healthcare workers are vaccinated. Most have a booster shot, or will soon be required to have one, which helps mitigate some of the dangers.

Dr. Wachter went on to say that if the hospital needs an essential worker back right away, the best thing to have them do is care for coronavirus patients since they're already infected, and the nurses won't have to worry about transmitting the virus to them.

Coronavirus in San Francisco



Dr. Wachter says based on testing done in UCSF's hospital, data shows one in ten people (or 10-percent) are testing positive for COVID-19 while showing no symptoms.

Based on that information, "one out of 10 people walking around on the streets or in the restaurant with you, has COVID," he says.

RELATED: 'Two steps back': Grim sense of déj vu as omicron surge impacts start of 2022

"A month ago in San Francisco, there were 50 cases a day. Today, there are about 1,500 being reported, and many cases like my son's are not reported. So, there are probably three times that many. So it's a blizzard of COVID. It's a massive amount of COVID. You have to assume that any space you go into someone has it."

He continued, "If there are more than five to 10 people there, undoubtedly someone has COVID."

The good news is, he says this amount of cases will probably last just another month, like what's happened in South Africa, "very quick up and very quick down."

His advice is to "hunker down" for a few more weeks until things get better.

VIDEO: SF restaurants closing amid omicron staffing issues
EMBED More News Videos

Several Bay Area restaurants are struggling to stay open in light of Omicron. With staff members testing positive, owners are having to make the difficult decision to close for a night or longer.



Copyright © 2022 KGO-TV. All Rights Reserved.