For almost as long as vaccines have existed, so has an anti-vaccination movement, made up of ordinary people or organised groups who oppose the use of some or all vaccines to prevent disease. Often, its claims are based on a fear or misunderstanding of vaccines rather than on accurate information and scientific data. 

Earlier this year, Africa Check was alerted to an article claiming that a “mass rollout” of “alleged measles vaccines” in South Africa was having a negative impact on children. 

Published by an organisation called Children’s Health Defense (CHD), the article makes a number of false claims, including that the measles vaccine, which is often given to children in schools, is somehow linked to the Covid-19 vaccine. 

The claims were shared on TikTok, Twitter, and Facebook by CHD and the author of the article, Shabnam Mohamed. The article has been shared many times by others on social media, sometimes with comments expressing distrust of the South African government or the vaccination of children. 

But South Africans should not be fooled by these scaremongering claims. We investigated who is behind them and fact-checked three of the most pernicious.

Shabnam Mohamed of the Children’s Health Defense

Mohamed describes herself as an activist, journalist and lawyer. She is also the executive director of the “Africa Chapter” of CHD. 

CHD was founded by Robert F Kennedy Jr, a prominent anti-vaccine advocate. Kennedy has been repeatedly criticised by experts and his own prominent family for making false claims about vaccines and vaccine safety.

Like Kennedy, Mohamed is an anti-vaccine campaigner. In addition to her work for CHD, she is the founder of an advocacy movement called Transformative Health Justice (THJ), and has sued to prevent the South African government from providing Covid-19 vaccines as part of the “#StopTheShots” campaign, which she also founded.

Mohamed references both #StopTheShots and a THJ project called “SA Vaers” in her CHD article about measles vaccines, without disclosing that she runs both.

Africa Check contacted Mohamed about the source of her claims and was promised a response. At the time of publication, none had been received.

Measles in South Africa

Measles is a highly contagious disease caused by a virus. The main symptoms are rash and fever.

The disease is more severe in infants. Children are usually vaccinated against measles when they are young. In South Africa, this usually means two vaccines at six and 12 months of age. Vaccines which protect against multiple diseases including measles are available through private healthcare providers for children aged 12 to 18 months. In this case, a booster vaccine should also be given before the age of five, Dr Kerrigan McCarthy, a specialist pathologist at the National Institute for Communicable Diseases' (NICD) Centre for Vaccines and Immunology, told Africa Check. 

South Africa has been experiencing a measles outbreak since late 2022. To prevent the outbreak from worsening, the NICD has launched a catch-up vaccination campaign, providing free measles vaccines to children aged six months to 15 years.

This is meant to close the immunity gap between the percentage of children who have been vaccinated in recent years, and the percentage who need to be vaccinated to prevent the disease from spreading. Children are eligible, and can be safely vaccinated whether they have missed a scheduled shot in the past, have had all of their regular vaccinations, or do not know their vaccination history.

Africa Check spoke to Dr Edina Amponsah-Dacosta, a medical virologist and vaccinologist, and Carmen Whitehouse, a master of public health student, both from the Vaccines for Africa Initiative (VACFA) at the University of Cape Town’s School of Public Health. In a joint response, they said that South Africa conducts regular measles vaccination campaigns “every three to four years” in children aged five and under, for the same reason. This is in line with the World Health Organization’s recommendations for measles vaccination, they said.

This claim is at the heart of the article. But Mohamed provides no reliable evidence for it.

“When it is given as an injection, [the measles vaccine] causes very few side effects. One in 20 children develop a fever, and one in 100 will develop a mild rash nine to 14 days after the vaccination,” McCarthy told Africa Check. 

Other estimates of the likelihood of side effects are similar. For example, a 2016 meta-analysis shared with Africa Check by Amponsah-Dacosta and Whitehead put these rates at 5 to 15% for fever (or one to three in 20 children) and 5% (one in 20) for rash.

A meta-analysis is a type of scientific study which combines the results of many other studies to find common trends. This provides very reliable evidence, as it minimises the impact of an unusual result or poorly conducted study on the overall findings. 

However, the meta-analysis emphasised that the rates of severe complications were far higher in children with measles than in vaccinated children. The study estimated that 2 000 out of every million unvaccinated children would die from measles infection, compared to an estimated zero deaths in a vaccinated group. 

While some side effects were to be expected, Mohamed suggested that the ones being reported were unusual. The “evidence” she provided was that “parents, doctors, and concerned community members” had reported to the South African Vaccine Adverse Event Reporting System (SA Vaers) “that children receiving the measles shot are experiencing swollen faces, headaches, fever, confusion”, among other symptoms.

SA Vaers is run by THJ, Mohamed’s anti-vaccine advocacy organisation. It’s an informal reporting system modelled on the US Vaccine Adverse Event Reporting System (Vaers), though the US system is operated by that country’s Centers for Disease Control and Prevention and Federal Drug Administration.

As Africa Check has previously explained, anyone can report an adverse event to Vaers, and these reports are not evidence of a link between a vaccine and an adverse event.

Vaers clearly warns that “a causal relationship cannot be established using information from VAERS report alone”. “Just because an adverse event happened after a person received a vaccine does not mean the vaccine caused the adverse event,” it cautions.

SA Vaers, on the other hand, contains no such disclaimer and even invites the public to “Report Negative Jab Effects”, implying that reported adverse events are the “effects” of vaccination.

The data published by SA Vaers includes reports of adverse events that are unlikely to be related to vaccination, such as reports of adverse events that began more than 100 days after vaccination, long after the 28-day period in which adverse events typically occur. SA Vaers does not appear to have investigated any of these reports, or made an attempt to exclude reports that are unconnected to vaccination.

Because SA Vaers’ “reporting, and investigation processes are unclear, there is every indication that the associations reported are unreliable”, Amponsah-Dacosta and Whitehouse told us.

Like the US-based official Vaers, the two scientists explained that adverse events following vaccination are often “not due to the vaccine itself but are often co-incidental events, human error during the administration of the vaccine or errors at the programmatic level”.

Vaccine Adverse Event Reporting Systems

SA Vaers does not provide details of the reports it has received about measles vaccines, although the article includes screenshots of WhatsApp messages Mohamed claims to have received. These claim that several children have had adverse reactions to the measles vaccine. 

None of the reports confirm a link between vaccination and adverse events. In fact, several of them give alternative explanations for why the children may be ill. One child who allegedly became ill after being vaccinated was, according to the WhatsApp messages in the article, diagnosed with mumps, another viral disease.

Many of the reports are also second- or third-hand. One WhatsApp message appears to have been forwarded to Mohamed by a social worker who received it from “a domestic worker”. It appears the domestic worker, in turn, passed on the information from a cousin whose daughter was vaccinated.

This kind of anecdotal evidence, like reports made to SA Vaers, does not prove a link between measles vaccines and adverse reactions.

The article says: “Questions are now being raised in the public whether the children are receiving traditional measles shots, mRNA based measles shots, or C-19 shots.” 

Messenger RNA, or mRNA, vaccines work by giving the body instructions to produce a specific protein found on the virus. The body’s immune system then learns to recognise the real virus, and produces antibodies, or proteins that are part of the immune system, that can protect the body if it comes into contact with the actual virus. 

However, “all measles vaccines are live attenuated vaccines”, McCarthy told Africa Check. “There are no measles vaccines that are mRNA vaccines.”

As evidence for her claim that these vaccines “could be” something other than standard measles vaccines, Mohamed linked to a March 2021 press release about a scientific paper in which researchers tested a potential vaccine against Covid-19 on hamsters, rats, and mice. The vaccine was created by modifying an existing measles, mumps, and rubella (MMR) vaccine. The paper says that the vaccine was only tested on rodents, and has not been produced for human use.

“This candidate vaccine has not been tested in any human trials in South Africa or elsewhere,” Amponsah-Dacosta and Whitehouse said.

The CHD article also links to an article about the same research, in which the scientists behind it imagine “one day incorporating a coronavirus antigen into the measles-mumps-rubella (MMR) vaccine as a way to produce COVID-19 immunity in kids”. However, this combination vaccine does not yet exist.

Mohamed admitted in the article that the only measles vaccine given to children by public health providers in South Africa was called MeasBio. As the NICD explains, it only protects against measles, and is not an MMR vaccine, although MMR vaccines are available through private healthcare providers in South Africa. It is also a live-attenuated vaccine, not an mRNA vaccine. According to the department of health, the measles vaccine should be administered in two injections at six and 12 months of age. 

While the article does not state outright that these vaccines are mRNA or combination measles and Covid-19 vaccines, it suggests that they could be, which is still incorrect.

“There are currently no approved measles and Covid-19 combination vaccines on the market in South Africa or elsewhere,” Amponsah-Dacosta and Whitehouse.

The implication that healthcare providers are lying about the contents of a vaccine or that Covid-19 and mRNA vaccines are strongly linked to adverse effects supports other false claims made by Mohamed, Kennedy, and other anti-vaccine conspiracy theorists.

Again, the article does not state that the measles vaccine can be shed, but raises the question suggestively, along with research to support it. 

It cites a 2019 paper in the journal Viruses to suggest that the measles vaccine can be detected in a person’s respiratory tract long after they’ve been vaccinated. Mohamed implies that the measles vaccine can be “shed”, “causing the virus to be spread to others”. 

Vaccine “shedding” is a common aspect of anti-vaccine conspiracy theories, particularly those surrounding Covid-19 vaccines. These suggest that people vaccinated against Covid-19 “shed” the Sars-CoV-2 virus, or part of it, and cause unvaccinated people to contract the actual disease.

This is false. It has been repeatedly debunked, including by Africa Check. Covid-19 vaccines cannot cause shedding of the Sars-CoV-2 virus.

Attenuated live virus vaccines

Shedding is possible, although very rare, with some vaccines, called attenuated live virus vaccines. These vaccines contain a weakened, or “attenuated”, form of the virus that causes the disease. This allows a person’s immune system to build up resistance to the virus, without getting the disease itself.

But even in these cases, shedding does not cause “the virus to be spread to others”. Because these vaccines use a weakened form of the virus, only the weakened forms of the virus can be shed.

The oral polio vaccine is an example of a vaccine that can be transmitted in this way, McCarthy told Africa Check. 

“However, because it is a vaccine strain, it does not cause symptoms. If people ‘catch’ the polio vaccine strain from someone who is vaccinated, it will have the effect of strengthening that person’s antibodies to polio, if they have previously received the polio vaccine, or it will vaccinate them, causing protective antibodies to develop.” 

Measles vaccines, including the MeasBio vaccine, are attenuated live virus vaccines. But this does not mean that people vaccinated against measles can transmit the disease to others, as the article suggests.

“Transmission of measles vaccine strains from a vaccinated person to an unvaccinated person has never been documented,” Amponsah-Dacosta and Whitehead told Africa Check.

Shedding as an anti-vaxx myth

The 2019 Australian study cited in the article tested for the presence of the measles virus and measles vaccine genetic material in samples collected during routine childhood measles testing from 2013 to 2017.

It detected some of the genetic material of MeVV (measles virus vaccine) in 141 of nearly 10 000 samples, some time after the children were vaccinated. This is not the same as detecting the actual measles virus (referred to as MeV), and the study did not suggest that MeVV could spread measles.

The article conveniently doesn’t quote the part of the paper where the authors say that “detection of MeVV RNA alone does not allow for any assessment of whether infectious virus is present”. 

It also omits: “We acknowledge that MeV vaccination still remains a safe and highly effective way of preventing the spread of MeV and our findings in no way contradict data on the effectiveness of the MeV vaccine. Importantly, our findings should not be used as a reason for leaving anyone unvaccinated against measles.”

Shedding as an anti-vaccine myth falsely implies that vaccination is dangerous not only to a person’s own health, but also to the health of those around them. This is the opposite of how vaccines actually work. Not only does vaccination minimise an individual person’s chances of contracting a disease, but if many people in a population have been vaccinated against a disease, it minimises the chance of the disease spreading. This protects everyone in that population.

Why are these claims so dangerous?

The claims in the article are easily disproved. They are either supported by poor circumstantial evidence (such as the weak link between sick children and vaccination), no evidence (for the claim that the vaccines are not ordinary measles vaccines), or evidence that directly contradicts the claims (such as the paper that emphatically supports vaccination as safe and effective). So why should we be concerned about these claims at all?

For one thing, these claims don’t need to be accurate to make readers feel scared. Simply making parents vaguely doubt that their children are being safely vaccinated, or that they are getting the right vaccines, can be enough to put them off. As one group of researchers wrote in a 2018 review of anti-vaccine movements: “Research has shown that even parents favorable to vaccination can be confused by the ongoing debate, leading them to question their choices.” 

Anti-vaxx movements have been linked to measles outbreaks, including in countries where the disease was previously well controlled. This is despite the fact that, as Amponsah-Dacosta and Whitehouse said: “Overall, severe complications after measles infection far out-weigh the rare severe adverse reactions following vaccination.”

These claims are also dangerous because they reinforce the legitimacy of other false claims and the people who make them. Children’s Health Defence and Robert Kennedy Jr frequently make false, potentially harmful claims about vaccines, and a parent drawn to this CHD article because of uncertainty about the measles vaccine may be led to believe other false claims. These include false claims that childhood vaccines are linked to autism or about the risks of Covid-19 vaccines.

This network effect is common in conspiracy theory circles. Research has shown that if a person believes in one conspiracy theory, they are very likely to believe in others, even if some of these conspiracy theories contradict each other.

Written by Keegan Leech, Researcher