Influenza: When to test and when to treat
Clearing up some confusion
We’re seeing rates of influenza A increase here in NYC. And everyone has been asking me what to do… so it inspired a quick newsletter.
It’s off season for a number of reasons.
Omicron led to increased precautions in December that likely halted the early spread.
Recently, policy changes led to less masking and fewer restrictions enabling flu to spread more.
While flu vaccine rates are OK (around that of a typical year), about half people take flu vaccines and of those… half of those get vaccinated by mid-october. That means 6 months later, now in mid-April even vaccinated individual’s protection is likely waning. Similar to what we see with COVID, while vaccinated individuals might get influenza they are less likely to get severe cases, have complications or require hospitalization.
But all of these local flu cases have led to the question… when do you test for influenza? Now that we are all covid testing experts, I wanted to explain how I approach this.
I test for influenza when there is significant community transmission (more than 1-5%) and when it will change my management of the child. This depends both on the timing of when symptoms start and when testing is being considered and the risk factors in the family.
If you can identify the flu early in illness (within 48 hours) it’s more likely that antiviral medication will help, though if you are high-risk taking it at any point may be recommended. If the child or someone the child lives with is high risk for complications of the flu we also may want to take antiviral medication. So these are the people who most need a test.
Oseltamivir (tamiflu) is still the main antiviral medication for flu as a 5 day course for treatment. Tamiflu reduces the duration of symptoms by 16-31 hours. For children antiviral medication has been shown to reduce the risk of secondary ear infections and need for antibiotics. While it is suspected that Tamiflu may reduce the likelihood of severe flu, hospitalization, or death this has not been proven, likely because it would require a large trial given the rarity of these complications in healthy children.
Since healthy children over 5 are less likely to have complications for the flu, they are also less likely to benefit from medication. Very widespread use of antiviral medication may lead to resistant strains, so we generally don’t always recommend it for healthy individuals over 5. Tamiflu has some side effects, but is generally OK. 8-16% of children vomit and 2-17% have headaches
If you or your child have risk factors or live with someone who does, Tamiflu can be a great option. People who I recommend to consider tamiflu (for full cdc list look here):
Under 5 years, but especially under 2
Household contacts of babies under 6 months
Over 65 or residents of nursing homes
Pregnant women up to 2 weeks postpartum
Non-hispanic black persons, hispanic or latino persons (if you are curious read about disparities leading to this guideline here. Black and Latino children are at twice the risk of hospitalization compared to white children)
For people who have asthma, epilepsy, cerebral palsy, sickle cell, kidney or cardiac problems, immunosuppression.
This is definitely a case of shared decision making. Some families are very anxious about influenza and hate their kids being sick and just want to do everything they can to decrease risk, and I don’t see myself as a gatekeeper. But for my own healthy kids I don’t test for influenza after 2, because I am not sure the benefit is justified, and frankly they have so many colds (particularly pre-covid restrictions) it would have been a lot of healthcare visits. The only reason I might test would be if they seemed sick with a high fever without an obvious source.
To emphasize, if you have a newborn in the home and older kids, even if you say to yourself, the older child may not need tamiflu, taking the medication would possibly decrease the risk of transmission to the baby who we want to protect. Or even if you don’t want to use tamiflu for a healthy older child, you may still want to test because if the baby gets sick you will want the opportunity to start the medication as soon as possible as it works best early on. In fact it works so well, that if influenza seems highly likely in these situations (a high risk individual with a known exposure) it’s recommended that you not wait for a test and just give tamiflu when symptoms start.
I wanted to talk about this because everyone is asking me my thoughts when their kids get sick… but also because next year we’re going to be in a different place for viral testing.
Consumer at home covid testing has become very accessible and common, and most of these companies are pivoting to offer covid and flu tests. So more flu testing will mean more flu detection, potentially earlier flu detection and potentially increase our ability to deliver tamiflu. It will lower barriers for people like me - maybe I will test my kids for flu if I can just do it at home and do so in that first 24-48 hours of illness.
But I hope that we selectively guide those at the higher risk of getting very sick from flu towards using tamiflu. Because I want tamiflu to keep working and if a lot of people use it the virus will evade. That said if you or your loved one is high risk for sure use it.
And I hope that we won’t also have people saying “oh my child is sick but negative for covid and flu so I will send them to school or that birthday party”. Because there are other viruses out there we don’t want to spread like RSV, metapneumovirus, and adenovirus.
If I’ve lead to more confusion than clarity please drop your questions in the comments. But I hope you and your family stay well!
If you missed it… Huff Post asked me to comment on the utility (or lack of utility) for antibody testing children for COVID here.
Earlier this season, I talked to The NY Times about why children under 8 need two doses of influenza vaccine the first year they are eligible for vaccination.
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