Limited manufacturing capacity, supply chain disruptions and a dearth of personnel with specialized skills are all challenges vaccine makers are facing as they race to produce contracted quotas of COVID-19 vaccines that were developed and authorized in record time.

As of Jan. 31, the two companies with FDA emergency use vaccine authorizations had released about 32% of the 200 million vaccine doses that they contracted to provide to the U.S. government by March 31, according to a new Government Accountability Office (GAO) report that looks at how federal agencies are trying to overcome the hurdles.

The unprecedented 10-month development and authorization of the vaccines was made possible by compressing the timelines of traditional vaccine development and review, overlapping some clinical trials and animal studies, relying on data from other vaccine development and scaling up manufacturing even as the vaccines were still being tested.

But when it comes to manufacturing enough vaccines to meet the need, timelines can’t be compressed, especially when manufacturing facilities and supplies are limited.

“Before the COVID-19 pandemic, most existing vaccine manufacturing capacity was already in use,” according to the GAO report. Thus, new capacity had to be created or production capacity shifted from other products.

In addition, there was a shortage of fill-finish facilities with the capacity to handle the millions of doses of new vaccines. “That type of facilities shortage can lead to production bottlenecks,” the GAO said.

Vaccine companies are partnering with the government’s Operation Warp Speed (OWS) program to expand production capacity to meet the need. In at least one case, the Biomedical Advanced Research and Development Authority (BARDA) helped a company identify an additional manufacturing partner to increase production, the GAO noted. In other instances, the U.S. Army Corps of Engineers is overseeing construction projects to expand capacity at existing vaccine manufacturing facilities.

The Corps also is addressing some of the supply chain issues dogging manufacturers by supporting companies making products such as cell culture media and glass vials that are essential to vaccine production. Yet the vaccine supply chains remain strained by the global demand for certain goods, export restrictions and workforce disruptions caused by the pandemic, the GAO said.

As a result, vaccine makers face delays in obtaining materials, including disposable reactor bags, reagents and certain chemicals. Some told the GAO they are having to wait four to 12 weeks for items that were typically available for shipment within one week before the pandemic.

To help mitigate such disruptions, BARDA worked with each of the six vaccine companies involved in OWS to create a list of critical supply needs that are common across their vaccine candidates. In December, the U.S. Department of Defense (DOD) and Health and Human Services placed prioritized ratings on 18 supply contracts for vaccine companies under the Defense Production Act. In addition, OWS officials are working with U.S. Customs and Border Protection to expedite necessary vaccine manufacturing equipment and goods coming into the U.S., according to the report.

U.S. government agencies also have had to step in to help fill the increased demand for personnel with the specialized skills required to run complex vaccine manufacturing processes. Vaccine companies have reported challenges during the pandemic in filling mid to upper management positions, which serve as the technical points of contact for production questions and are responsible for managing safety, quality and good manufacturing practice compliance, the GAO said.

To fill those gaps last year, 16 DOD personnel were assigned to serve as quality control staff at two vaccine manufacturing sites until the companies could hire the needed experts. The DOD personnel were still in place at the sites as of last month.

Meanwhile, OWS officials are working with the U.S. Department of State to expedite visas for key technical personnel, including technicians and engineers, to assist with installing, testing and certifying critical equipment manufactured overseas.

The U.S. is not alone in facing COVID-19 vaccine manufacturing challenges. Acknowledging that it underestimated the difficulties inherent in the mass production of the vaccines, the European Commission said Feb. 10 that it has organized a task force to identify production problems and help find solutions to them.