While researchers around the world work on a vaccine for COVID-19, one group of people is in no rush to see one emerge, with some prominent figures even saying they might refuse it when one does become available.

Anti-vaxxers have made headlines in the past for their opposition to vaccinations against diseases like measles. But amid a global pandemic that has claimed over 190,000 lives, forced people indoors and brought major economies to a standstill, this attitude now presents a serious health risk.

Vaccine hesitancy

Vaccines prevent two to three million deaths per year, according to the World Health Organization (WHO). They have helped eradicate diseases like smallpox and, around the world, massive campaigns to vaccinate children have reduced the incidence of polio, diphtheria, Hepatitis B, rubella, measles, and pneumococcal disease.

But vaccine hesitancy, when people refuse or delay vaccinations despite their availability, has been on the rise lately, to the extent that the WHO named it as one of the top 10 threats to global health for 2019.

Read more: Measles outbreak feared as coronavirus halts immunization drive

Proper coverage against preventable diseases only works as long as the majority of the population has been inoculated and in the UK, vaccination rates among infants have dropped steadily in recent years, according to National Health Service data. Coverage against measles, which is especially contagious, fell to just 90.3 percent last year, far below the 95-percent threshold deemed necessary to adequately protect the population.

In the U.S., a study by the Health Testing Centers also saw a drop in overall vaccination rates from 2009 to 2018, with 26 states below the 95-percent target for measles and polio," a sad testament to the surge in so-called 'vaccine hesitancy' over the last decade," it noted.

Reluctance to vaccinate has since caused a number of measles outbreaks in developed countries. Last year, the disease returned to the UK, Greece, and the Czech Republic where it had previously been eliminated, and the U.S. recorded its highest number of cases in 25 years.

A victim of its own success

While people in countries like Rwanda and Bangladesh almost universally trust vaccines, only 72 percent of people in North America and 59 percent of people in Western Europe think they are safe, according to a survey last year by the Wellcome Trust, a UK research charity.

One notorious anti-vaxxer argument has revolved around now-debunked claims that the vaccine against measles causes autism. Other misconceptions listed by the U.S. Centers for Disease Control (CDC) include the belief that vaccines can have harmful side effects and even cause death, that giving a child multiple vaccinations will overload the immune system and that people who have been vaccinated are more likely to get the disease. 

Anti-vaccination groups online have been accused of spreading misinformation and often display a strong distrust of government and belief in conspiracy theories.

But part of the complacency is also due to the vaccines' own success.

"People have forgotten how dangerous these diseases can be," Robin Nandy, the chief of immunization at UNICEF, the UN Children's Fund, noted in an interview with the Daily Mail last year.

Doctors point out that diseases like measles or tetanus were widespread just one or two generations ago, but today, most people have never seen them with their own eyes, leading them to downplay their seriousness.

A new situation

The COVID-19 pandemic may now be changing all that.

Lockdown measures, school closures, instructions to work from home and limits on where and for how long people can go out, alongside dramatic images of overcrowded hospitals and an ever-increasing death toll, have brought home the reality of a deadly virus for many.

Warnings by health experts that life will not go back to normal and large gatherings will not be possible until a cure and a vaccine can be found – potentially not before 2021 – are also making many reconsider the trade-offs.

According to the UK's Vaccine Confidence Project (VCP), there are signs that opposition to vaccines is diminishing in some countries in the wake on the epidemic. "If we had had a vaccine for this, we wouldn't be locked up in a room, the economies wouldn't be crumbling, we would have been a whole different world," VCP director Heidi Larson told CNN. "I think it definitely is provoking people to rethink a lot of things," she noted.

In Italy, one of the countries worst hit by COVID-19, anti-vaxxer arguments have "virtually disappeared", said one virologist cited by Reuters.

A warning

Still, others are sticking to their beliefs. World tennis number one Novak Djokovic made headlines this week after coming out against vaccination in order to restart tennis tournaments.

"Personally I am opposed to vaccination and I wouldn't want to be forced by someone to take a vaccine in order to be able to travel," he said during a Facebook live chat. Other big names in the sport had previously said that resuming competition without a vaccine would be too dangerous given how much players and staff travel.

While the world waits for a vaccine against COVID-19, the WHO has warned that other diseases risk rearing their head again if immunization efforts slow down due to the epidemic.

"Disease outbreaks must not remain a threat when we have safe and effective vaccines to protect us," WHO Director-General Tedros Adhanom Ghebreyesus said in a statement Friday at the start of World Immunization Week.

"While the world strives to develop a new vaccine for COVID-19 at record speed, we must not risk losing the fight to protect everyone, everywhere against vaccine-preventable diseases. These diseases will come roaring back if we do not vaccinate."

(Cover image: A nurse administers a vaccination to a six-year-old boy in Mount Vernon, Ohio, May 17, 2019. /AP)