Your home flu test is positive. What next?

The latest in-home tests not only detect COVID but also flu. So, if you take one and it’s positive for flu strain A or B, what should you do next?

Don’t just tough it out, contact a medical professional, advised Kenneth Jackson, M.D., a family medicine provider at Cape Cod Healthcare’s Fontaine Primary Care in Harwich. A flu shot should minimize symptoms but doesn't prevent you from getting the flu or infecting others, he said.

“Just because you might be in the population where you do not have side effects or are at risk for hospitalization, you may be around others that are at risk for hospitalization,” he said. “Having you be treated for the flu would be in their benefit to help minimize the spread.”

The rapid home flu tests work on the same principle as the now-familiar self COVID tests. You use a nasal swab to collect mucus from inside your nose, swish it in the reactive liquid and then wait 15 minutes to see if the mixture produces a reaction on the test strip. The test detects COVID or flu virus proteins – called antigens – that are present in the infected mucus from your nose. The recent flu tests detect strain A and B, with A being the most common. The strains differ in that A affects both humans and animals, while B affects only humans; symptoms and treatment are the same, Dr. Jackson said.

Home tests can be good indicators but aren’t always accurate, he said. Sometimes that’s due to user error – for example, not sticking the nasal swab far enough up your nose. If you’re uneasy about doing it yourself, Dr. Jackson suggests asking someone else to take the swab.

“Sometimes it’s tough doing it yourself because you have angst about putting it up too far or hurting yourself,” he said. “And so, having someone else do it can work out a little better.”

Also, it can take a couple of days for symptoms to evolve enough to show up on a home test, he said.

If your test comes out negative but you still feel flu-ish, ask your primary care physician or CCHC Urgent Care for a PCR (polymerase chain reaction test), a molecular test that can detect smaller amounts of flu virus.

Why Test?

Why bother testing? Flu can be risky for the very young, whose immune systems are not yet developed, or the very old, whose immune systems have weakened. “And, the older you are, the more likely you are to have chronic conditions that can put you at a risk of developing complications, such as COPD, diabetes, asthma, things along those lines,” he said.

Clinicians like to treat flu within 48 hours of the onset of symptoms, Dr. Jackson said. The most common treatment is an antiviral medication called oseltamivir, or Tamiflu, for up to 10 days, either for someone who actually has the flu or as a prophylactic treatment for someone who has been exposed.

“But even if you’re past that 48 hours and you have a higher risk of hospitalization, most providers will treat you,” Dr. Jackson said. “For example, say you’re the caregiver for your mom or your aunt or someone and you’re at high risk of passing [flu] on, or that person is at high risk for hospitalization.”

Some flu patients not considered at high risk might need respiratory support or intravenous fluids to prevent dehydration, he said.

So, if your home flu test is positive, contact a medical provider. Some will do virtual visits to save you from spreading it throughout a doctor’s office, Dr. Jackson said. If it’s negative and your symptoms persist, ask about next steps, such as a PCR test.

Home tests “are just a tool,” he said. “The goal is to help minimize the spread and really minimize the exposure to those at risk – the reason why we do the flu shot seasonally. There’s nothing wrong with [home] testing, just ask for appropriate help when something comes back positive or if you have a question about it.”