In 15 months after the introduction of the vaccination in Brazil, G2P(4) rotavirus strain has replaced all other strains, even though it was only seen in 19%-30% of cases prior to the introduction of vaccination. Effectiveness of the vaccine (Rotarix) against this strain was 77% among children of 6-11 months of age, and -24% (negative) among children over 12 months of age. More: [1], [2].
It is reported here, that after the introduction of vaccination in Brazil, regular rotavirus strains got replaced with the new GP12(8) strain. Strain replacement also took place in Paraguay==https://www.ncbi.nlm.nih.gov/pubmed/20213281] and in Argentina.
One year after introduction of vaccination in Brazil, Hib meningitis incidence decreased by 69% (from 2.62 to 0.81 in 100,000). Hia meningitis (H. influenzae type a) increased 8-fold (from 0.02 to 0.16 in 100,000).
Clinical virulence of Hib and Hia is the same. Hia mortality rate was 23%.
After the mass MMR vaccination campaign in Brazil with the Japanese strain of mumps (Urabe), an outbreak of aseptic meningitis began. The risk of disease increased by 14-30 times.
The fact that Urabe strain is associated with aseptic meningitis was already known, but Brazilian authorities decided to use this strain anyway, as it is cheaper and more effective than the Jeryl Lynn strain (which is used in the US), and because they thought the risk of meningitis was quite low.
In France, vaccination with the same strain did not cause a meningitis outbreak. The authors attribute this phenomenon to the fact that the outbreaks in Brazil were observed mainly in the large cities, where people live close to hospitals. Moreover, a large number of children had been vaccinated in a very short time. These factors made it possible to identify the outbreak.
The authors worry that such side effects could lead to more people refusing vaccination. They say that people’s belief in the benefits of vaccination is no longer strong enough on its own, and that more and more people refuse vaccination, and that it would not hurt to also record side effects of the vaccination.
Xavante is a Native American tribe in Brazil, which is virtually untouched by civilization. A 1964 study found that they were all infected with poliovirus, and almost all of them had antibodies to the three serotypes of the virus, but they had neither paralytic polio nor any symptoms of the disease. They also had antibodies to other diseases – measles, whooping cough, influenza, salmonella, but most of the infections were virtually asymptomatic for them.
After the start of vaccination, the colonization of vaccine serotypes decreased significantly, but it increased for non-vaccine ones. H. influenzae bacteria were found in vaccinated people 2-5 times more often than in unvaccinated ones. (Sao Paulo, Brazil)
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