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: , .
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.
After vaccination began, colonization with vaccine serotypes was significantly reduced and increased by a non-vaccine one.2-5 times more often than in unvaccinated people (Sao Paulo, Brazil)Prevention of Haemophilus influenzae type b (Hib) meningitis and emergence of serotype replacement with type a strains after introduction of Hib immunization in Brazil. 2003, Ribeiro, J Infect Dis
A year after the start of vaccination in Brazil, the number of cases of meningitis from Hib decreased by 69% (from 2.62 to 0.81 per 100,000).The number of cases of meningitis from Hia (hemophilic rod of serotype A) increased 8-fold (from 0.02 to 0.16 per 100,000.) Clinically, the virulence of Hib and Hia does not differ, the mortality from Hia was 23%.Studies on the Xavante Indians of the Brazilian Mato Grosso. 1964, Neel, Am J Hum Genet
Xavante is a virtually indestructible tribe of Indians in Brazil, it turned out that they are polio viruses, almost all had antibodies to the three serotypes of the virus, but they do not have paralytic poliomyelitis or any symptoms of the disease. there were antibodies to other diseases - measles, whooping cough, flu, salmonella, but most infections passed in them almost asymptomatically.Outbreak of aseptic meningitis associated with mass vaccination with a urabe-containing measles-mumps-rubella vaccine: implications for immunization programs. 2000, Dourado, Am J Epidemiol
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.