Japan launched its coronavirus vaccination program on Wednesday, five months ahead of the Tokyo Olympics as the World Health Organization (WHO) reported a fall in new cases around the world.

Many are wondering if the campaign will reach enough people, and in time to save a Summer Olympics already delayed a year by the worst pandemic in a century.

"Hopefully vaccinations ... can change the situation here," nurse Rino Yoshida told national broadcaster NHK after she got one of the first shots, as reported by Agence France-Presse (AFP).

With infections topping 109 million and more than 2.4 million deaths, the pandemic has devastated the global economy and populations are growing increasingly frustrated with financially painful restrictions that authorities and experts say are necessary to fight the virus.

Despite recent rising infections, Japan has largely dodged the kind of cataclysm that has battered other wealthy countries' economies, social networks and health care systems. But the fate of the Olympics, and the billions of dollars at stake should the games fail, makes Japan's vaccine campaign crucial.

Japanese officials are also well aware that China, which has had success eradicating the virus, will host next year's Winter Olympics, something that heightens the desire to make the Tokyo Games happen. A big problem as the vaccines are rolled out – first to medical workers, then the elderly and then, possibly in late spring or early summer, to the rest of the population – are worries about shortages of the imported vaccines Japan relies on, and a long-time reluctance among many Japanese to take vaccines because of fears of relatively rare side effects that have been played up by the media in the past.

The late rollout will make it impossible to reach so-called "herd immunity" against the virus before the Olympics begin in July, experts say. The vaccination drive has the support of the government, but there's widespread wariness, even opposition, among citizens to having the games at all. About 80% of those polled in recent media surveys support the cancellation or further postponement of the Olympics because of concerns about the virus.

According to a survey conducted by Kyodo News in January, 35.3% of those polled were in favor of canceling the Games, while 44.8% said the event should be postponed once again.

Organizers have outlined measures they say will keep the Games safe even without requiring participants to be vaccinated or quarantined on arrival. But there are fears among the Japanese public and experts that the precautions may not be enough for a global event, even as the WHO on Tuesday reported a slowing of the pandemic. New infections worldwide fell by 16% last week, while the number of new deaths also dropped 10% week-on-week, based on figures up to Sunday.

"The fire is not out, but we have reduced its size," WHO Director-General Tedros Adhanom Ghebreyesus said Monday.

About Japanese 40,000 doctors and nurses considered vulnerable to the virus because they treat COVID-19 patients were in the group getting their first dose starting Wednesday and are scheduled to receive their second dose beginning March 10. Japan lags behind many other countries. The government only gave its first vaccine approval Sunday for the shots developed and supplied by Pfizer Inc.

The U.K. started inoculations on Dec. 8, while the U.S. began its campaign on Dec. 14, with about 15 million people vaccinated by mid-February. Vaccines were rolled out in Germany, France, Italy and many European countries in late December.

Japan fell behind because it asked Pfizer to conduct clinical trials with Japanese people, in addition to the trials already conducted in six other nations. Japanese officials said this was necessary to address worries in a country with low vaccine confidence.

"I think it is more important for the Japanese government to show the Japanese people that we have done everything possible to prove the efficacy and safety of the vaccine to encourage the Japanese people to take the vaccine," Japanese Vaccine Minister Taro Kono said. "So at the end of the day we might have started slower but we think it will be more effective.

Japan's mistrust of vaccines is decades old. Many people have a vague unease about vaccines, partly because their side effects have often been played up by media there. Half of the recipients of the first shots will keep daily records of their condition for seven weeks; that data will be used in a health study meant to inform people worried about the side effects.

"We would like to make efforts so that the people can be vaccinated with a peace of mind," Chief Cabinet Secretary Katsunobu Kato told reporters. Japan, where the development of its own vaccines is still in the early stages, must rely on foreign-developed vaccines initially.

According to The Associated Press (AP), Japanese Prime Minister Yoshihide Suga on Wednesday acknowledged the importance of strengthening vaccine development and production capability as "important crisis management" and pledged to provide more support.

Supplies of imported vaccines are a major worry because of supply shortages and restrictions in Europe, where many are manufactured. Supplies of imported vaccines will determine the progress of the vaccination drive in Japan, Kono said.

The first batch of the Pfizer vaccine that arrived Friday is enough to cover the first group of medical workers. The second batch is set for delivery next week. To get the most vaccine from each vial, Japanese officials are scrambling to get specialized syringes that can hold six doses per vial instead of five by standard Japanese-made syringes.

After the front-line health care workers receive their vaccines, inoculations of 3.7 million more health workers will begin in March, followed by about 36 million people aged 65 and older starting in April. People with underlying health issues, as well as caregivers at nursing homes and other facilities, will be next before the general population receives its turn.

Many on social media expressed hopes that inoculation is the first step to eradicate the pandemic.

"Finally COVID-19 vaccination has started this morning in Japan too! Hope the situation gets better and people can start traveling again," one social media user wrote on Twitter.

Suga has said he's determined to achieve a safe and secure Olympics as "proof of human victory against the pandemic," but the prospect is uncertain given the state of the infections.

Japan is currently under a partial state of emergency in part because Suga's virus measures were too lax and slow. Critics say many medical workers are now helping out in the vaccination drive at a time when Japanese hospitals are already strained by the daily treatment of COVID-19 patients.

There is worry hospitals will have no additional capacity to cope with the large number of overseas visitors the Olympics would involve.