by Alan Hinman, MD

What’s the value of vaccination? The answer to that question may be different for each of us. For me, measles is the best example.

Alan Hinman - 032711 (2)I graduated from medical school in 1961, two years before measles vaccine was introduced in the United States. That year, 428,919 cases of measles and 434 deaths due to measles were reported in the United States.

The actual number of measles cases that occurred was much larger (by a factor of 8-10) because virtually every child in the US had measles before the age of 15, so the number of cases each year, on average, should be about the same as the number of children born (4.2 million in 1961).

The reasons for the discrepancy included the fact that not all children with measles were taken to the doctor, and doctors did not report all cases they saw. The number of deaths recorded was probably also an undercount because many children died from complications of measles such as pneumonia, and were considered pneumonia deaths rather than measles deaths.

Globally, it was estimated that between 5 and 8 million children died each year as a result of measles.

In countries where malnutrition is common, as many as three to five percent of children who acquired measles died as a result. By contrast, in the US the death toll was one death per 1,000-10,000 cases.

The introduction of measles vaccine in 1963, and its subsequent widespread use, led to a dramatic decline in reported incidence of measles (see figure) to the extent that, in the late 1960s, we began efforts to eliminate or eradicate measles from the US.hinman measles 2

In 1978, a goal was set to eliminate measles from the US by October 31, 1982. Elimination was defined as having no cases of measles in the US that could not be traced to a foreign source.

Aided by enactment and enforcement of school immunization requirements in all 50 states, we got down to very low levels. However, we did not achieve elimination in the 1980s. In fact, there was a resurgence of measles from 1989-1991 that resulted in more than 55,000 cases and 100 deaths.

Two factors were primarily responsible for the resurgence—unimmunized pre-school children living in low socio-economic status urban areas, and vaccine failures in school-aged children who had received only one dose of measles vaccine (a single dose of measles vaccine will protect 95-98% of children, leaving 2-5% unprotected; a second dose will protect 95-98% of those who did not respond to the first dose).

The measles resurgence led to recommendations for a two-dose schedule for measles vaccine and also led to establishment of a Childhood Immunization Initiative and enactment of a law establishing the Vaccines For Children (VFC) Program, which provided an entitlement to free, government-purchased vaccine for children less than 18 years of age who are uninsured, on Medicaid, Alaska Native, or American Indian.

In addition, children who have insurance that does not cover a given vaccine may receive it free from a Federally Qualified Health Center. Approximately one-half of US children are eligible for VFC.

The combination of increased Federal government support to State Health Departments along with VFC has resulted in the highest immunization levels ever achieved in young children – 90.8% of 19-35 month old children in the US in 2012 had received at least one dose of measles-containing vaccine (usually combined with mumps and rubella vaccine as MMR).

Reported measles cases declined even further and, in 2000, an expert panel (of which I was privileged to be a member) concluded that measles had been eliminated from the United States – there was no longer continuous circulation of measles. I also participated in a panel in 2012 that concluded that measles elimination had been sustained.

In the past 20 years, we have had only 3 measles deaths in the US, none of them since 2003. Contrast that with the 434 deaths recorded in 1961 alone!

There has been dramatic progress in the rest of the world but with considerable variation. The entire region of the Americas achieved measles elimination in 2002 using a strategy that included mass immunization campaigns targeting all children 1-15 years of age to rapidly achieve high coverage (“catch-up”), reaching high levels of coverage with routine immunization activities (“keep-up”), and “follow-up” campaigns every 3-4 years targeting children born since the last campaign, as well as good surveillance for measles and proper case management.

This approach has been slightly adapted and implemented in other parts of the world and has resulted in dramatic declines in measles deaths. From the pre-vaccine era estimate of 5-8 million deaths per year, the number declined by 1980 to an estimated 2.5 million and by 2000 to 548,000, nearly an 80% reduction compared to 1980.

In 2012, there were an estimated 122,000 deaths due to measles around the world, a further 75% reduction compared to 2000. Nonetheless, this is still 122,000 deaths too many.

All six of the World Health Organization’s Regions have now set measles elimination target dates no later than 2020, and there is growing interest in global eradication of measles, a target colleagues and I had called for in 1982. It is gratifying to see that it may come to pass. The recent resurgence in the US is troubling but I believe we can deal with it.

I look forward to the day when measles is just a memory rather than a current killer.

¹(Hopkins DR, Hinman AR, Koplan JP, Lane JM. The case for global measles eradication. Lancet, i:1396 1398, 1982)