Vaccine developers slumped as Johnson & Johnson appeared to be nearing regulatory approval for its shot in the U.S., which would be the third available in the country.

The biotechnology companies racing to come up with new shots for COVID-19 were mostly lower after a bumpy week. Pfizer Inc. and its German vaccine partner, BioNTech SE, slid on Friday. The duo were down less than 1 per cent each, despite positive real world-results of their vaccine in Israel, as investors continue to assess how long the pandemic could persist and how big the future vaccine market may be.

For Johnson & Johnson, the largest drugmaker in the country by market value, the prospect of its vaccination winning regulatory approval wasn’t enough to stop shares from tumbling 2.4 per cent. A panel of outside experts is weighing the company’s one-shot regimen on Friday as the Food and Drug Administration considers a speedy authorization.

Analysts are expecting the FDA to clear J&J’s shot before the end of the month, potentially as soon as this weekend.

Companies trailing the market leaders also tumbled. Arcturus Therapeutics Holdings Inc. slid as much as 5.1 per cent. The small-cap company has been developing its own one-shot vaccine. What’s good for the reopening and the end of the pandemic may not be so great for runner up vaccine developers. Most of them fell earlier in the week following Israeli vaccine results that suggested immunizations would work to curb the virus.

AstraZeneca Plc fell 1 per cent. Late-stage results from a U.S. trial are expected within the next few weeks. Vir Biotechnology Inc., a company working on antibody treatments for COVID-19, sank 3.6 per cent.

Moderna Inc., the only other company authorized to sell its COVID shots in the U.S., bucked the trend to climb on Friday, on pace for its second day of gains. The biotech firm has risen 46 per cent so far this year after a 434 per cent rally in 2020. The Cambridge Mass.-based company’s US$18.4 billion in COVID contracts met some of the most bullish expectations on Wall Street even as investors continue to debate the longevity and potential size of the vaccine and booster shot market.

With the threat of new variants, analysts don’t sound sure either. Michael Yee at Jefferies said the market for Moderna’s vaccines in 2022 could range anywhere from US$10 billion to US$30 billion.

Novavax Inc. also advanced, climbing 1.4 per cent on Friday. The stock is still down 19 per cent for the week. Phase 3 data for the Maryland-based biotech’s shot from a study spanning the U.S. and Mexico is expected by April.