Manufacturers of COVID-19 vaccines are focusing on boosters.

It is uncertain how many booster doses will be required in the coming future as the pandemic continues.

After distributing as many doses as they could over the last 18 months, COVID-19 vaccine manufacturers are altering gears and prepping for a smaller, more competitive booster shot market. Pfizer and Moderna executives said they estimate the majority of those who wished to be vaccinated against COVID-19 have already been vaccinated, more than 5 billion people worldwide. Most COVID-19 vaccinations in the coming year will be booster doses or initial inoculations for children, which are currently awaiting regulatory approval around the world. Even if global demand drops, Pfizer, which partners with Germany's BioNTech, and Moderna envision a major role for themselves in the vaccine market. AstraZeneca and Johnson & Johnson's involvement in this market are projected to diminish as their shots become less popular and effective.

"It becomes a very competitive game with companies battling it out with pricing and for market share, even for vaccines that are considered to be the best, like Pfizer and Moderna," said Hartaj Singh, an analyst at Oppenheimer & Co. It is unclear how many booster doses will be required. Only a small percentage of the population is currently recommended for second booster doses in various countries. It is also uncertain whether vaccine manufacturers would market a revised shot this fall and every fall after that, as they do with flu vaccines to match circulating strains, and what effect that will have on dwindling demand. Adults who are still unvaccinated, according to Pfizer CEO Albert Bourla, are unlikely to seek vaccinations now, more than two years into the pandemic.