Cost of Zika Outbreak in U.S. Could Be High, Analysts Warn

1% infection rate equates to $1.2 billion in medical expenses and lost productivity

Even a relatively mild Zika outbreak in the United States could result in more than $183 million in medical costs and productivity losses, while a more-severe outbreak could cost $1.2 billion, according to a computational analysis led by researchers at the Johns Hopkins Bloomberg School of Public Health. Their study was published in PLOS Neglected Tropical Diseases.

The researchers estimated the potential impact of a Zika virus outbreak based on a variety of epidemic sizes. They focused on five Southeastern states and Texas––the U.S. locations most populated by Aedes aegypti, the mosquito most likely to carry the disease.

Although many people with Zika virus infection (ZVI) are asymptomatic or show only mild flu-like symptoms, ZVI during pregnancy can cause severe birth defects, such as microcephaly or other brain deformities. There have also been reports of Guillain–Barré syndrome (GBS), a rare nervous-system disease, in regions affected by the Zika virus. No treatments or vaccines for ZVI are currently available.

“This is a threat that has not gone away. Zika is still spreading silently, and we are just now approaching mosquito season in the United States, which has the potential of significantly increasing the spread,” said study leader Bruce Y. Lee, MD, MBA. “There is still a lot we don’t know about the virus, but it is becoming clear that more resources will be needed to protect public health. Understanding what a Zika epidemic might look like, however, can help us with planning and policy-making as we prepare.”

With government funding for Zika detection, prevention, and control still uncertain, policymakers need estimates of Zika costs to help guide funding decisions, according to the researchers. It is unclear how many people in the U.S. have already been infected and how many more cases will occur this summer, but the findings, they say, are further evidence that the costs of any Zika outbreak would be high.

For their research, Lee and his colleagues developed a computational model based on different rates of spread of Zika if it were to hit Florida, Georgia, Alabama, Mississippi, Louisiana, and Texas, taking into account factors such health care costs and productivity losses.

Even when assuming an attack rate––the percentage of the population that eventually gets infected––of only 0.01%, the model estimated that Zika virus would cost more than $183 million and cause more than 7,000 infections, two cases of microcephaly, and four cases of GBS. An attack rate of 1.0% would cause more than 704,000 infections, 200 cases of microcephaly, and 423 cases of GBS. The 1% attack rate could also result in $1.2 billion in medical costs and productivity losses. A 10% attack rate could result in more than $10.3 billion in medical costs and productivity losses.

These attack rates would be substantially lower than those observed in French Polynesia (66%), on Yap Island in Micronesia (73%), and in the state of Bahia in Brazil (32%), where the current Zika outbreak is believed to have originated. The attack rates are also lower than recent outbreaks of chikungunya, a virus spread the same way as Zika, including an outbreak in Puerto Rico (24%).

After much delay last year, Congress allocated $1.1 billion for mosquito-control efforts and vaccine development, as well as for emergency health care for Puerto Rico, where more than 35,000 people contracted ZVI. Lee believes far more money may be necessary, given his estimates for medical care.

“Without details regarding the Zika-prevention measures that would be implemented and how effective these may be, it is unclear what percentage of these costs may be averted,” he said. “But our model shows it is very likely that preventing an epidemic––or at least finding ways to slow one down––would save money, especially since epidemics like Zika have hidden costs that aren’t always considered.”

Source: Johns Hopkins Bloomberg School of Public Health; May 3, 2017.