By Stephanie Stahl

PHILADELPHIA (CBS) — A third COVID-19 vaccine could be available next week. Today, Johnson & Johnson released results from its phase three trial that showed its vaccine works with just one shot, but it’s not as effective as the two that are already out.

We got a little spoiled with the Pfizer and Moderna vaccines, which are 95% effective.

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Johnson & Johnson’s vaccine doesn’t offer as much protection but doctors say they’re all good, and people should get whatever is available.

“There’s no question that this vaccine’s gonna be a gamechanger,” said Dr. Mathai Mammen with Johnson & Johnson.

Johnson & Johnson tested its vaccine on 44,000 participants. It was 66% effective overall at preventing moderate to serious symptoms, and much more protective — 85% — against severe cases of COVID-19.

Two potential big advantages are that it’s a single dose and can be stored in a regular refrigerator.

But the Pfizer and modern vaccines, which require freezers and two doses, are 95% effective.

“The efficacy of this Johnson & Johnson vaccine — the data that’s been released so far is still extremely good by any vaccine standards and will make a huge difference in the ability to control the pandemic,” said Dr. John Wherry, the director of Penn’s Institute for Immunology.

Wherry says any vaccine is better than none, especially with the new more contagious variants. Johnson & Johnson says its vaccine is protective against several mutations, including the one from South Africa.

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“We need to keep an eye on these variants and they’re concerning but the vaccines are working very well,” Wherry said.

“I’d like to see how things break down,” said Dr. Paul Offit.

Offit, a Philadelphia vaccine expert, is on the FDA Advisory Board, which will recommend whether or not the Johnson & Johnson vaccine should get emergency use authorization.

He still needs to review the data but is encouraged.

“We have another vaccine which is highly effective in keeping you out of the hospital. That is an advantage in a situation where we don’t have enough vaccines,” Offit said.

The U.S. government has pre-ordered about 100 million doses, but Johnson & Johnson only expects to have fewer than 10 million available for February — that’s if it gets cleared by the FDA.

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Stephanie Stahl