- Vaccination rates have improved dramatically since the 1980s, however, the growth in coverage has stalled in recent years.
- Vaccines creates broad and deep fields of protection against infectious diseases if a big enough portion of the population is vaccinated. If the percentage of people refusing vaccines reaches a certain threshold, disease outbreaks can happen. Measles, for instance, has returned in many countries.
- In the U.S., a third of respondents to a CNN poll said they would not take a COVID-19 vaccine.
- Concerns as disparate as fear of side-effects to mind control and autism have led to an increase in vaccine hesitancy.
VANCOUVER. Despite centuries of success in eliminating disease and decades of steady expansion of vaccination programs, the growth in vaccination rates appears to have stalled in pockets around the world.
The slowdown in vaccination rates can lead to the reemergence of diseases thought to have been controlled or eradicated, like measles, and may make it more difficult to contain new diseases, such as COVID-19.
Many more people use vaccines or are covered by vaccination programs now than just a few decades ago but gaps remain. Some 13.5 million children go unvaccinated globally every year, according to Our World in Data.
The portion of people who identify themselves within a spectrum that ranges from the ‘vaccine cautious’ to the ‘vaccine hesitant’ and all the way to the ‘serious antivaxxers’ is relatively small, but it is a loud and committed group. And social media has created an echo chamber that amplifies anti-vaccine sentiments.
The message does not have to spread very much for holes to appear in the net of immunity that vaccines create. Gaps are already appearing. Outbreaks of measles have surfaced in places as disparate as Hong Kong, Samoa, and the U.S. If the holes in the vaccination net are big enough, they could render a potential vaccine for COVID-19 virtually useless.
Building herd immunity
Speaking to CNN on June 28, the top U.S. infectious disease specialist Dr. Anthony Fauci said he would be satisfied with a vaccine that is effective between 70 to 75% of the time. For such a vaccine to be effective, a significant portion of the population would have to take the vaccine.
Many people in the U.S. say they would not be willing to take a COVID-19 vaccine and that reticence could make it difficult to reach the levels of herd immunity needed to contain the virus. The most effective vaccine to date has been the measles vaccine, which can have up to 98% efficiency.
In a May poll in the U.S. done by CNN, a third of respondents (33%) said they would not take a COVID-19 vaccine.
“There is a general anti-science, anti-authority, anti-vaccine feeling among some people in this country,” Fauci said.
And having a third to a quarter of Americans take a vaccine that is only 75% effective may not be enough to stop the runway progress of the virus. Rather, it would leave a big gaping hole for COVID-19 to continue spreading.
Success and resistance
Researchers are still unclear on whether opponents of vaccines are more active now due to the pandemic or simply more visible because of all the focus on a vaccine.
At times, and particularly in the U.S., the opposition to vaccines has been linked to individual freedom. For others, the reasons for vaccine hesitancy or outright opposition range from concerns about side-effects to fears of individual component elements to conspiracy theories about how vaccination programs are tools to control populations. While there is seldom any fact behind many of these fears, there have been times when there has been a certain amount of justification.
In Pakistan, for example, vaccine hesitancy has spiked as a result of suspicion, fear and a healthy dose of erroneous information as well as a vaccination campaign that was used as a cover in the U.S. search for Osama Bin Laden in 2011.
Still, vaccination rates have improved steadily and significantly since the middle of the last century with a brief pause in the 1990s .
For instance, the rate of global tuberculosis vaccination was just 15% in 1980 but rose to 81% by 1990 and 89% by 2010. It has not increased since.
Coverage of a first dose of measles vaccination was 16% in 1980, 73% a decade later and 84% by 2010. By 2018, the rate had only inched up to 86%.
Vaccination rates did not expand significantly between 1990 and 2000, nor have they since 2010, according to World Health Organization (WHO) data tracked by Our World in Data. The WHO says immunization rates have remained static for the last few years.
In general, wealthier countries have higher rates of vaccination but there are exceptions. Burundi, Rwanda and Bangladesh all have high rates. Countries with large poor populations may also have lower rates of immunization.
As vaccination rates stall, vaccine hesitancy is on the rise.
The most visible impact of this rise in hesitancy may be on measles. The WHO says the number of reported cases of measles has risen 30% since 2016. In the first three months of 2019, there were 300% more reported cases than in the first three months of 2018. Cases began spiking in 2017.
“The resurgence of measles is of serious concern, with extended outbreaks occurring across regions, and particularly in countries that had achieved, or were close to achieving measles elimination,” said Dr. Soumya Swaminathan, Deputy Director General of Programmes at the WHO in November 2018. “Without urgent efforts to increase vaccination coverage and identify populations with unacceptable levels of under- or unimmunized children, we risk losing decades of progress in protecting children and community.”
Measles is very contagious and very preventable with two doses of a vaccine. It was, for all intents and purposes, eradicated in most rich nations.
The case of polio
Vaccines have been quite successful at eliminating disease and few of these successes are as widespread and visible as the eradication of polio. There were about 350,000 cases of poliomyelitis – the dreaded polio – every year before 1988. Last year, there were about 100.
The only way to eliminate the disease is to interrupt the transmission of the poliovirus and that can really only be done through vaccination.
In 1980, just 21% of all one-year-olds around the world were vaccinated for polio. By 1990, the rate had increased to 75% and to 84% by 2010. Progress has stalled since then, rising just another percentage point by 2018.
Still, as a result of widespread vaccination, polio does not exist in much of the world. According to the WHO,the world is 99% of the way towards eradicating the disease altogether.
Mass-scale vaccination globally has been facilitated by the Global Polio Eradication Initiative, launched in 1988. So far, a global coalition of private and public sector stakeholders have invested $17 billion to vaccinate more than 2.5 billion children.
Today, polio remains endemic in just two countries: Afghanistan and Pakistan. Nigeria had polio until recently but was to be declared free of the disease this year.
Polio is a disease that is particularly vulnerable to vaccination.
It is infection caused by one of three strains of a virus that infects the nervous system and can cause total paralysis, sometimes in a matter of hours. Symptoms include fever, fatigue, headache, vomiting, stiffness in neck and pain in the limbs. At times, polio can kill by seizing up breathing muscles, and this happens in 5 to 10% of cases. In one in 200 patients, the paralysis caused by the virus is irreversible.
It is caused by one of three strains of the poliovirus and none of them can live long outside the human body, although the virus can be found in dirty water or in unsanitary conditions. Only one of the three types remains in circulation, with type 2 eradicated in 1999 and type 3 not seen since 2012, according to the WHO.
There are two main types of polio vaccine, one of which is given orally and is quite cheap, costing as little as $0.14.
These oral vaccines used in the poorer countries around the world rely on a weak dose of the polio virus to generate immunity, but it has also led to an increase of cases of vaccine-derived poliovirus (VDPV). Over time, VDPV has mutated and led to sporadic cases of polio, according to the Centers for Disease Control and Prevention.
In 2019, outbreaks of VDPV were recorded in Philippines, China, Myanmar, Pakistan and several African countries, all of them with lower vaccination coverage.