The CDC is changing the way it reports people who contract COVID-19 after they have been vaccinated against the virus, drawing some questions and ire from those it affects.
Starting May 14, the agency will only report COVID cases among vaccinated people if the person has been hospitalized or died. According to a CDC webpage, the change aims “to help maximize the quality of the data collected on cases of greatest clinical and public health importance.”
However, some scientists are concerned by the move, which they say could lead to missing data, Bloomberg reported. Others argue the data so far about breakthrough cases––or those COVID-positive cases where the person was already inoculated––reveal few alarming trends. That means there likely isn’t anything to miss by narrowing the data to the most severe cases.
When the CDC made its decision, just over 9,000 out of more than 95 million vaccinated people contracted COVID-19. That’s likely an undercount, as some breakthrough cases are expected. The figure is nonetheless positive news for the efficacy of the vaccines.
“COVID-19 vaccines are effective and are a critical tool to bring the pandemic under control,” the agency stated. “However no vaccines are 100% effective at preventing illness. There will be a small percentage of people who are fully vaccinated who still get sick, are hospitalized or die from COVID-19.”
The breakthrough cases are also giving scientists more insight into different COVID-19 variants, which are spreading globally. It’s unclear what effect, if any, the various COVID vaccines have against the variants of the virus. According to the CDC, “there is some evidence that vaccination may make illness less severe.”
Currently, the CDC is relying on state health departments to report breakthrough cases, with the federal agency aiming to sequence respiratory specimens to identify virus lineage that causes the illness. It has developed “a national COVID-19 vaccine breakthrough REDCap database where designated state health department investigators can enter, store, and manage data for cases in their jurisdiction.”
The system of reporting is partly why the CDC believes the data will represent an undercount.
“This surveillance system is passive and relies on voluntary reporting from state health departments which may not be complete,” the agency said. “Also, not all real-world breakthrough cases will be identified because of lack of testing. This is particularly true in instances of asymptomatic or mild illness. These surveillance data are a snapshot and help identify patterns and look for signals among vaccine breakthrough cases.”