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Vaccine effectiveness – correcting misunderstandings about COVID-19 vaccines

vaccine effectiveness

I keep reading how people think that when a COVID-19 vaccine is reported to have 95% effectiveness it must mean that they have a 5% chance of catching COVID-19 after being vaccinated. But effectiveness doesn’t quite mean that, and I wanted to clarify.

Part of the reason this needs clarification is that until we have herd immunity against COVID-19 (along with all of the variants), it’s important to practice all of the public health measures like wearing a mask and social distancing even if you have been vaccinated.

So, this will be a little bit of mathematical analysis of vaccine effectiveness, so that you know what it means.

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2017 flu vaccine effectiveness – getting the facts straight

2017 flu vaccine effectiveness

The upcoming flu season may be a rough one. A strain of the influenza A, H3N2, is showing up in small clusters of outbreaks throughout the USA. Unfortunately, the 2017 flu vaccine effectiveness against the H3N2 may be lower than expected.

We will get into the details further in this post, but I do not want to bury the headline. This does not mean the 2017-18 flu vaccine is ineffective – the quadrivalent 2017 flu vaccine effectiveness against three of four flu strains is still fairly high. The flu vaccine is extremely important in stop lots of flu strains, and just because it may have an issue with one of the four strains, does not imply that it is useless.

Let me repeat that, just in case someone misses the point – only one of the four strains of flu in the 2017-18 vaccine may have lower effectiveness. The vaccine remains highly effective against the other four strains. Continue reading “2017 flu vaccine effectiveness – getting the facts straight”

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Varicella vaccine effectiveness – more supporting evidence

varicella vaccine effectiveness

The varicella vaccination for chickenpox was introduced in the mid-1990’s in the USA and has been associated with substantial and statistically significant declines in incidence, hospitalizations and deaths attributable to chickenpox. Thanks to  real science, more evidence supports varicella vaccine effectiveness.

Despite the beliefs of vaccine refusers, who have stated emphatically that chickenpox is not dangerous, the real complications from a varicella infection are numerous and serious:

  • dehydration
  • pneumonia
  • bleeding problems
  • infection or inflammation of the brain (encephalitis, cerebellar ataxia)
  • bacterial infections of the skin and soft tissues in children including Group A streptococcal infections
  • blood stream infections (sepsis)
  • toxic shock syndrome
  • bone infections
  • joint infections

Since I was born before the chicken pox vaccine, I contracted the disease, which eventually lead to encephalitis. I have vivid memories of being a five year old child and being admitted into the ER with a brain infection. It’s a memory I’d rather not have.

The anti-vaccine gang love to question the effectiveness of vaccines. But they don’t have evidence of that, whereas, I’m going to present some powerful evidence that the varicella vaccine is highly effective in preventing chickenpox.

Continue reading “Varicella vaccine effectiveness – more supporting evidence”