SCIENCE science.orgmanufacturing is affecting production of es-
sential non-COVID vaccines in several ways.
Shortages of input materials
Manufacturers report that they are facing
difficulties in timely access to consumable
components such as bioprocessing bags,
filters, tubing, and laboratory supplies.
Culture media—an essential raw mate-
rial for most vaccines—and vials, syringes,
and ampoules have been backordered,
with promised delivery times as long as 18
months. Several of those shortages are ex-
pected to persist for a considerable time.
These input material shortages are due
to the rapid scale-up of COVID-19 vaccine
manufacturing, exacerbated by distribution
challenges. Because suppliers for certain
critical components are limited in number
and concentrated in a few countries, access
was difficult early in the pandemic when
goods distribution was greatly constrained.
In addition, emergency measures may have
contributed to prioritizing the manufacture
of COVID-19 vaccines over the manufacture
of other products ( 3 ).
Multiple factors are magnifying the
impact of these shortages. Vaccine manu-
facturers have moved toward lean supply
chains, limiting their reserve stocks of in-
put materials and becoming more sensi-
tive to supply disruptions. Manufacturers
have also shifted away from stainless-steel
bioreactors to single-use assemblies and
bioprocessing bags. As a result, they are
critically dependent on sophisticated con-
sumable components that are typically not
interchangeable.Manufacturing capacity constraints
Some manufacturers report that they have
repurposed facilities or production capac-ity built for other vaccines to manufacture
COVID-19 vaccines. In some instances,
capacity expansion for non–COVID-19
vaccines has been hampered by delays in
equipment availability and installation,
with lead times of up to 18 months. Con-
tract manufacturing organizations (CMOs)
have limited availability to address ca-
pacity constraints for other vaccines be-
cause they are being used extensively for
COVID-19 vaccine production.
Human resources are also limited.
Reassignment to COVID-19 vaccine pro-
duction and testing, facility lockdowns,
and absences due to quarantines and ill-
nesses have caused shortages of experi-
enced personnel, including laboratory
staff and engineers. These shortages have
delayed some manufacture, testing, and re-
lease of essential vaccines and continue to
constrain capacity.Postmanufacturing concerns
To monitor product quality, some regulators
require submission of every vaccine lot for
review and release. This process has been
slowed owing to the increased workload for
regulatory agencies and because COVID-19
vaccines have been prioritized for regula-
tory review, delaying the availability of
other vaccines. Updates to the manufactur-
ing or testing for vaccines that are already
licensed also require regulatory review and
may be delayed for similar reasons. Regula-
tory delays have also been a bottleneck for
countries that import vaccines.
More broadly, manufacturers are re-
evaluating their product portfolios; this
may result in reprioritization or even dis-
continuation of less profitable vaccines in
favor of COVID-19 vaccine manufacture.
Vaccines with lower prices and smaller
market shares, such as polysaccharide vac-
cines for pneumococcus and meningococ-
cus , are at greater risk.CURRENT AND ANTICIPATED DISRUPTIONS
Supply disruptions have occurred for pneu-
mococcal conjugate vaccines, measles-
containing vaccines, diphtheria and teta-
nus-containing vaccines, and inactivated
poliovirus vaccines. Disruptions have in-
cluded delivery delays and reduced quanti-
ties of specific products (see the table). In
most cases, manufacturers have been able
to secure stocks of input materials and
procurement agencies have been able to
access alternative sources, minimizing the
impact on vaccination programs.
In the latter part of 2021, consumables
and single-use materials such as biopro-17 DECEMBER 2021 • VOL 374 ISSUE 6574 1439A health assistant applies a vaccine to a child in a
rural area of Bangladesh in September 2020.