FLU BLOCKED in Southern Hemisphere, but story may differ above equator.

JOHANNESBURG — Winter is ending in the Southern Hemisphere and country after country — South Africa, Australia, Argentina — had a surprise: Their steps against covid-19 also apparently blocked the flu.

But there’s no guarantee the Northern Hemisphere will avoid twin epidemics as its own flu season looms while the coronavirus still rages.

“This could be one of the worst seasons we’ve had from a public health perspective with covid and flu coming together. But it also could be one of the best flu seasons we’ve had,” Dr. Robert Redfield, director of the Centers for Disease Control and Prevention, told The Associated Press.

U.S. health officials are pushing Americans to get vaccinated against the flu in record numbers this fall, so hospitals aren’t overwhelmed with a dueling “twindemic.”

It’s also becoming clear that wearing masks, avoiding crowds and keeping your distance are protections that are “not specific for covid. They’re going to work for any respiratory virus,” Redfield said.

Ordinarily, South Africa sees widespread influenza during the Southern Hemisphere’s winter months of May through August. This year, testing tracked by the country’s National Institute of Communicable Diseases is finding almost none — something unprecedented.

School closures, limited public gatherings and calls to wear masks and wash hands have “knocked down the flu,” said Dr. Cheryl Cohen, head of the institute’s respiratory program.

That not only meant lives saved from flu’s annual toll, but it “freed up our hospitals’ capacity to treat covid-19 patients,” Cohen added.

Flu hasn’t disappeared, a World Health Organization report cautioned this month. While “globally, influenza activity was reported at lower levels than expected for this time of year,” it found sporadic cases are being reported.

But international influenza experts say keeping schools closed — children typically drive flu’s spread — and strict mask and distancing rules clearly helped.

“We don’t have definitive proof, but the logical explanation is what they’re doing to try to control the spread of [the coronavirus] is actually doing a really, really good job against the flu as well,” said Richard Webby of St. Jude Children’s Research Hospital, who is part of a WHO committee that tracks flu evolution.

In contrast, the U.S. and Europe didn’t impose coronavirus rules nearly as restrictive as some of their Southern neighbors.

So the CDC is urging record flu vaccinations, preferably by October. Redfield’s goal is for at least 65% of adults to be vaccinated; usually only about half are.

The U.S. expects more than 190 million doses of flu vaccine, about 20 million more than last year. States are being encouraged to try drive-thru flu shots and other creative ideas to get people vaccinated while avoiding crowds.

Massachusetts has mandated flu vaccination for all students — from elementary to college — this year. Typically only some health care workers face employment mandates for flu vaccine.

In the United Kingdom, Prime Minister Boris Johnson likewise is urging widespread vaccination.

To be clear, the flu vaccine protects only against influenza — it won’t lessen the chances of getting the coronavirus. Vaccines against covid-19 are still experimental; several candidates are entering final testing to see if they really work.