Zika Vaccine: A Study Weighs Cost and Effectiveness
Vaccines vary in their effectiveness. Flu vaccines have ranged in recent years from 19% to 60% effective in protecting people from contracting the flu, according to the U.S. Centers for Disease Control, while the effectiveness of the measles vaccine is well over 90%.
But sometimes vaccines are worthwhile even if their efficacy is limited, depending on the cost of developing and delivering them, and the cost of treating the condition that they’re designed to avert. A new study from the CUNY Graduate School of Public Health and Health Policy about the costs and benefits of a Zika vaccine is a case in point.
If a pregnant woman is bitten by a mosquito carrying the Zika virus, her baby may develop severe birth defects, including the devastating congenital brain disorder known as microcephaly. Men infected with Zika can also transmit the virus to others through sex. Zika has also been linked to Guillain-Barré syndrome.
Zika carries economic costs as well. In wealthy countries such as the U.S. the estimated cost of care for one child with microcephaly has been calculated as high as $10 million.
Fortunately, Zika vaccines are in the works. The CUNY SPH study, published in the American Journal of Preventive Medicine, shows that Zika vaccines given to women of childbearing age could be worth the cost under certain conditions — even if the vaccine is effective only 25% of the time.
“The study shows that a Zika vaccine doesn’t have to offer near perfect protection to be valuable,” Sarah M. Bartsch, project director of Public Health Computational and Operations Research (PHICOR) at CUNY SPH and lead author on the study, said in an interview with the school.
In a high-income country, the study found, a Zika vaccine of just 25% efficacy that lasts for one year could be cost effective as long as the infection risk is at 0.6% or less for women of childbearing age and 0.2% or less for pregnant women, and if the vaccine costs $50 or less. In a low-income country, a vaccine of 25% efficacy that lasts for one year would save the country money if it were administered only to pregnant women, if infection risk was at 0.3% or less, and if the vaccine cost $10 or less.
The researchers found these numbers by creating a computer model using simulated data for women in North, Central, and South America age 16 to 50 years old. The model considers their probability of getting pregnant and their susceptibility to Zika, along with costs of treatment and severe disease effects over time. The model allowed researchers to calculate threshold situations in which the vaccine can save a country money.
The results can help policymakers and stakeholders understand what’s needed in a vaccine, and who should receive it. The results also help researchers and manufacturers understand that a vaccine with seemingly low efficacy might still be worth developing, and how to price it —something the study shows varies by country.