One Indian Company Sold 22 Percent of the World's Vaccine Doses in 2023, and Each Batch Starts With a Stored Seed and Ends With a Regulator's Release

The World Health Organization’s market report for 2023 puts one Indian company, Serum Institute of India, at 22 percent of all vaccine doses bought worldwide that year, out of roughly 7 billion. Bharat Biotech is listed at 9 percent and Biological E at 5 percent, so the three firms, based in Pune and Hyderabad, add up to 36 percent of the volume.

Every one of those doses comes out of a regulated chain. A stored stock of cells or seed organisms sits at one end, and a regulator’s release of each batch sits at the other. For vaccines that UN agencies buy, WHO adds a further layer called prequalification.

Three firms, a third of the world’s doses

The WHO report counts doses procured in 2023 across 207 countries and buying channels, from 116 manufacturers. Serum Institute’s 22 percent made it the largest by volume. For comparison, Pfizer held 11 percent of volume that year, down from 26 percent in 2022 when COVID-19 shots dominated.

Serum Institute says on its own website that it has produced and sold more than 1.5 billion doses, used in around 170 countries. That matches the WHO share, since 22 percent of about 7 billion is roughly 1.5 billion. Bharat Biotech’s March 2026 anniversary release says it has delivered more than 9 billion doses over 30 years to more than 125 countries and now makes 20 vaccines. India’s older and larger business of supplying generic medicines is a separate story, told in how India became the world’s pharmacy.

WHO’s slide summary for 2024, published on 17 December 2025, puts the world market at 7.2 billion doses and says Serum Institute’s volume was twice that of the next largest manufacturer. It also shows how much two regions lean on Indian makers: companies headquartered in India supplied more than half of the vaccines procured in WHO’s Africa region and more than 65 percent in its Eastern Mediterranean region.

Some newer technologies sit in very few hands. For mRNA vaccines, the type that won the 2023 Nobel Prize in medicine, WHO says two manufacturers supplied 95 percent of the volume in 2024.

A frozen vial comes first

WHO’s good manufacturing practice guidance for biological products says that vaccines grown in microbial or cell culture should be made from a system of master and working seed lots or cell banks. The reason it gives is to prevent the genetic properties of the culture from drifting over repeated subcultures.

A master cell bank is a quantity of well-characterised cells, divided into many containers and stored under defined conditions. A working cell bank is derived from it, and one or more of its containers is used for each production culture. Seed lots do the same job for viruses and bacteria. The approved dossier fixes the maximum number of generations between the bank and the finished vaccine, and WHO says that number should not be exceeded.

The first bank gets full characterisation, including genetic identification, and its viability and purity are rechecked on a schedule afterwards. While a bank is being built, WHO says, no other living or infectious material should be handled in the same area or by the same staff.

Growing, purifying, filling

After the bank comes production. Canada’s National Research Council, describing its own vaccine plant, lays out a typical sequence. Cells are grown in bioreactors, which are tanks with controlled nutrients, temperature, acidity and oxygen, and the culture is moved into successively larger tanks. That stage can take several days or weeks.

Downstream, cell debris and other unwanted material are removed to leave the purified active ingredient, called the drug substance. The Council says this can take three to five days. The drug substance is then diluted to the right concentration, with an adjuvant (an added ingredient that strengthens the immune response) if the vaccine uses one. It is filled into sterile vials by aseptic equipment, which keeps microbes out, and the result is the drug product, the vaccine as it is sold.

WHO’s guidance also treats contamination as a design problem. Because culture conditions are built to make cells and microbes thrive, it asks manufacturers to control unwanted microbial load, endotoxins (fragments of bacteria that can cause fever) and viruses of animal or human origin. Its definition of inactivation covers the step used for killed vaccines: reducing the infectivity of microorganisms to an acceptable limit, or detoxifying toxins, by chemical or physical change. The sources used here do not describe the Indian plants step by step, so the sequence above is the general one.

The paperwork that travels with every batch

For vaccines, WHO says a batch processing record and a summary protocol should be prepared for each batch for the regulator’s lot release. The summary protocol is, in WHO’s definition, a document summarising all manufacturing steps and test results for a lot, certified and signed by the responsible person at the company. The person the company designates as responsible for quality assurance or quality control must approve it, and its format is settled with the regulator when the vaccine is licensed.

WHO also sets retention periods. Samples of the finished product, in final packaging, are kept for at least one year after the expiry date, so that they remain available for later testing.

What India’s regulator does with a lot

The Central Drugs Standard Control Organisation, or CDSCO, is India’s national regulatory authority for vaccines, according to its own draft guidance on vaccine approval. Vaccines fall under the Drugs and Cosmetics Act of 1940, the Drugs and Cosmetics Rules of 1945 and the New Drugs and Clinical Trials Rules of 2019. Power is shared with state licensing authorities, which inspect the factories and prepare the manufacturing licence for the central authority to approve.

That licence requires three things, the draft says: compliance with good manufacturing practice verified by inspection, marketing approval for the product, and an analytical report from the Central Drugs Laboratory showing the vaccine meets specification.

Release comes after licensing. The draft says each lot of vaccine, imported or made in India, must be released by the Central Drugs Laboratory before sale or distribution, and that release rests at minimum on a review of summary lot protocols. CDSCO’s page on the laboratory at Kasauli calls it the national control laboratory for vaccines and antisera for human use, and says it receives around 7,000 batches a year for testing, pre-release certification or both.

The Medical Dialogues trade site reported on 5 April 2020 that CDSCO told the laboratory it could release domestically made vaccine lots during the COVID-19 lockdown by reviewing summary protocols case by case, with samples to follow when logistics recovered. Manufacturers had to send a certificate of analysis and an undertaking to recall any lot found faulty. That account rests on the trade report, not on the circular itself.

What WHO prequalification asks for

Prequalification is WHO’s check that a vaccine is fit for purchase by UN agencies. WHO India says it is a precondition for manufacturers to sell through UN buying agencies.

A vaccine has to be on WHO’s two-year priority list, hold a marketing authorisation, and come from a country whose regulator WHO has confirmed, through its Global Benchmarking Tool, to be at the required maturity level. Applicants send a letter of intent, attend a pre-evaluation meeting, submit a dossier laid out like an international common technical document, and supply vaccine samples for WHO’s own testing along with lot summary protocols. WHO’s review covers the production process, quality control and clinical data, and it inspects the manufacturing site.

Approval is not permanent. WHO describes yearly reporting, periodic reassessment, targeted lot testing and follow-up of quality complaints for products already on the list. At the end of 2023 it listed 158 prequalified vaccines from 44 manufacturers, and 65 percent of the vaccine volume procured that year was prequalified.

India’s regulator meets the maturity condition. A WHO team re-benchmarked India’s vaccine regulatory system from 16 to 20 September 2024 and found it functional at Maturity Level 3, the same level it reached in 2017. WHO’s representative to India, Roderico Ofrin, said the result “will boost confidence, trust and reliance on India’s regulatory system.” WHO’s market report counts 34 countries at that level or higher for vaccine manufacturing as of September 2024.

The reliance Ofrin describes has a practical form. WHO’s page on national control laboratories says that when recipient countries can rely on the lot release done by the producing country’s regulator, access to prequalified vaccines is faster.

What the Biological E polio case shows

Prequalification is tied to the stages a site actually carries out. The Global Polio Eradication Initiative reported on 13 February 2026 that WHO had prequalified novel oral polio vaccine type 2, a vaccine used against outbreaks of vaccine-derived poliovirus, as made by Biological E. Until then the company had been approved for filling and finishing bulk vaccine supplied by PT Bio Farma of Indonesia. The new approval covers manufacture of the full vaccine, making Biological E the second full producer after PT Bio Farma.

The initiative says Biological E is expected to produce 600 million doses a year and that it has added 700 million doses to the global stockpile since March 2024.

How much of UNICEF’s supply is Indian

UNICEF delivered 2.790 billion vaccine doses to 105 countries in 2023, its Supply Annual Report says. WHO’s market report puts UNICEF at 33 percent of global volume, which makes it the single largest buyer of vaccines.

The share that comes from India is harder to pin down. UNICEF’s report lists India third among countries by value of supplies and services invoiced, at $482.1 million, behind the United States and Belgium, out of $5.244 billion in total procurement. That is about 9 percent by tuput’s own division, and it covers every kind of supply, not only vaccines. A UNICEF Supply Division slide from December 2022 says more than half of the vaccines it procures come from developing countries, without naming India.

The most specific official share in the documents checked for this article is a Gavi release datelined New Delhi on 6 January 2016, which said 60 percent of all Gavi-procured vaccines were manufactured in India. That figure is a decade old, and UNICEF’s 2023 annual report publishes no comparable split of doses by supplier country.