| https://www.cdc.gov/vaccines/vpd/measles/index.html > The MMR vaccine is very safe and effective. Two doses of MMR vaccine are about 97% effective at preventing measles; one dose is about 93% effective. Prevention of Measles, Rubella, Congenital Rubella Syndrome, and Mumps, 2013 Summary Recommendations of the Advisory Committee on Immunization Practices (ACIP) at https://www.jstor.org/stable/24832555 > One dose of measles-containing vaccine administered at age ≥12 months was approximately 94% effective in preventing measles (range: 39%–98%) in studies conducted in the WHO Region of the Americas (141,142). Measles outbreaks among populations that have received 2 doses of measles-containing vaccine are uncommon. The effectiveness of 2 doses of measles-containing vaccine was ≥99% in two studies conducted in the United States and 67%, 85%–≥94%, and 100% in three studies in Canada (142–146). The range in 2-dose vaccine effectiveness in the Canadian studies can be attributed to extremely small numbers (i.e., in the study with a 2-dose vaccine effectiveness of 67%, one 2-dose vaccinated person with measles and one unvaccinated person with measles were reported [145]). This range of effectiveness also can be attributed to age at vaccination (i.e., the 85% vaccine effectiveness represented children vaccinated at age 12 months, whereas the ≥94% vaccine effectiveness represented children vaccinated at age ≥15 months [146]). Furthermore, two studies found the incremental effectiveness of 2 doses was 89% and 94%, compared with 1 dose of measles-containing vaccine (145,147). Similar estimates of vaccine effectiveness have been reported from Australia and Europe (Table 1) (141). No mention of vitamin C. Given that "After exposure, up to 90% of susceptible persons develop measles", it seems very unlikely that differences in vitamin C play an important role. What are your sources? I found nothing on PubMed nor Google Scholar, though I did find that vitamin C is promoted to antivaxxers (eg, http://www.amcli.it/wp-content/uploads/2019/03/bmj-measles-f... ). You write "depend strongly on nutrition deficiencies", which my cited article describes as "In low to middle income countries where malnutrition is common, measles is often more severe and the case-fatality ratio can be as high as 25%". That's calorie deficient, but not specifically vitamin deficient. |
Child mortality due to measles is 200 to 400 times greater in malnourished children in less developed countries than those in developed ones. In addition, measles brings about consumption of nutrients in marginally nourished children, so they will also do worse if not supplemented during infection.
[1] https://www.karger.com/Article/Abstract/413843