promote myths, conspiracy theories, and misinformation linking the two. A developing tactic appears to be the "promotion of irrelevant research [as] an active aggregation of several questionable or peripherally related research studies in an attempt to justify the science underlying a questionable claim". Vaccination during illness Many parents are concerned about the safety of vaccination when their child is sick. Moderate to severe acute illness with or without a fever is indeed a precaution when considering vaccination. Vaccines remain effective during childhood illness. The reason vaccines may be withheld if a child is moderately to severely ill is because certain expected side effects of vaccination (e.g. fever or rash) may be confused with the progression of the illness. It is safe to administer vaccines to well-appearing children who are mildly ill with the common cold. Natural infection Another common anti-vaccine myth is that the immune system produces a better immune protection in response to natural infection when compared to vaccination. However, strength and duration of immune protection gained varies by both disease and vaccine, with some vaccines giving better protection than natural infection. For example, the HPV vaccine generates better immune protection than natural infection due to the vaccine containing higher concentrations of a viral coat protein, while also not containing proteins the HPV viruses use to inhibit immune response. While it is true that infection with certain illnesses may produce lifelong immunity, many natural infections do not produce lifelong immunity, while carrying a higher risk of harming a person's health than vaccines. For example, natural varicella infection carries a higher risk of bacterial superinfection with Group A streptococci. Natural measles infection carries a high risk of many serious, and sometimes life-long, complications, all of which can be avoided by vaccination. Those infected with measles rarely have a symptomatic reinfection. Most people survive measles, though in some cases, complications may occur. Among those that experience complications, about 1 in 4 individuals will be hospitalized and 1–2 in 1000 will die. Complications are more likely in children under age 5 and adults over age 20. Pneumonia is the most common fatal complication of measles infection and accounts for 56-86% of measles-related deaths. Possible consequences of measles virus infection include laryngotracheobronchitis, sensorineural hearing loss, and—in about 1 in 10,000 to 1 in 300,000 cases—panencephalitis, which is usually fatal. Acute measles encephalitis is another serious risk of measles virus infection. It typically occurs