Tuesday, May 9, 2023

Measles rears its ugly head again. Here are the data and the real bottom line. #1 Don't worry

A friend wrote about current TV warnings in Maine re measles: “One kid tested positive for measles AFTER being inoculated. Now there are warnings out for anyone who was anywhere near the kid in a variety of locations and times. Talk about building a fear porn extravaganza!”

Jamie McMahon  1   2 Ian M Mackay  3   4 Stephen B Lambert  4


Measles vaccines have been in use since the 1960s with excellent safety and effectiveness profiles. Limited data are available on detection of measles vaccine virus (MeVV) RNA in human subjects following vaccination. Available evidence suggests MeVV RNA can be identified up to 14 days after vaccination, with detection beyond this rare. In routine diagnostic testing, we used two real-time reverse transcription-polymerase chain reaction (RT-rPCR) assays targeting M and F genes to identify measles virus (MeV) and MeVV RNA. Confirmatory testing was performed with an N gene RT-rPCR, followed by sequence confirmation of RT-rPCR positives by semi-nested conventional RT-PCR assays targeting portions of the N, H, and L genes. We report detection and confirmation of MeVV RNA from the respiratory tract of 11 children between 100 and 800 days after most recent receipt of measles-containing vaccine. These novel findings emphasize the importance of genotyping all MeV detections and highlight the need for further work to assess whether persistent MeVV RNA represents viable virus and if transmission to close contacts can occur.

Conflict of interest statement

Jamie McMahon—no conflict; Ian M Mackay—no conflict; Stephen B Lambert—SBL is the current Chair of the National Measles and Rubella Elimination Working Party.

What does the CDC say? How Well Does the MMR Vaccine Work?

MMR vaccine is very effective at protecting people against measles, mumps, and rubella, and preventing the complications caused by these diseases. People who receive MMR vaccination according to the U.S. vaccination schedule are usually considered protected for life against measles and rubella. While MMR provides effective protection against mumps for most people, immunity against mumps may decrease over time and some people may no longer be protected against mumps later in life. An additional dose may be needed if you are at risk because of a mumps outbreak.

One dose of MMR vaccine is 93% effective against measles, 78% effective against mumps, and 97% effective against rubella.

Two doses of MMR vaccine are 97% effective against measles and 88% effective against mumps.

MMR is an attenuated (weakened) live virus vaccine. This means that after injection, the viruses cause a harmless infection in the vaccinated person with very few, if any, symptoms before they are eliminated from the body. The person’s immune system fights the infection caused by these weakened viruses, and immunity (the body’s protection from the virus) develops.

Some people who get two doses of MMR vaccine may still get measles, mumps, or rubella if they are exposed to the viruses that cause these diseases.

The [Nass] bottom line:

  1. Measles is a live virus vaccine that can reproduce and potentially shed for years from vaccinated individuals.

  2. We don’t know how many active US measles cases are due to vaccine strains because the CDC won’t tell us the results of testing, in order to avoid any negative effect on vaccination rates.

  3. Vaccination initially leads to 93% protection from 1 dose and 97% protection from 2 doses. Protection wanes over time, yet there are very few measles cases in the US yearly (usually under 100) and most can be traced to a case that came in from overseas.

  4. The last time a child died from measles in the US was 2003. He had had a bone marrow transplant and his natural immune system had been deliberately wiped out for the transplant. It was never announced whether his measles case was due to a vaccine strain or not.

  5. Don’t worry about measles! It is very rare; if you do get it you will have life-long immunity (unless your immune system is wiped out) and it can be effectively managed.

No comments: