Explained: How Kerala administered 74 lakh shots with 73 lakh vaccine doses

The state used the extra dose of vaccine added to compensate for wastage in each vial, at a time when states are short of vaccines.
A vaccine dose being extracted from a vial
A vaccine dose being extracted from a vial
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Kerala Chief Minister Pinarayi Vijayan confirmed in a tweet on Wednesday that the state had administered 74,26,164 vaccine shots to its people, using 73,38,806 vaccine doses. This means that Kerala provided 87,358 extra vaccine doses. Since each person gets two doses, this is equivalent to vaccinating an additional 43,679 people in the state. This is important as most states are reporting a shortage of vaccines and wastage, even as cases rise. 

So where did these extra doses come from?

Currently, the state has been supplied 73,38,806 doses of vaccine by the Government of India. Pinarayi’s tweet explains that Kerala used up extra vaccine added as ‘wastage factor’ in each vial of vaccine, to administer more doses. 

What is wastage dose or overfill

Vaccines come in tiny bottles called vials. In India, the stock of COVID-19 vaccines have been packaged and supplied in multi-dose vials, with enough vaccine to inoculate multiple people. 

In multi-dose vials, there can be a difference between the number of doses labelled on the vaccine vial and the actual number of doses that can be extracted from the vial. This is to compensate for any wastage or spillage that occurs while administering the vaccine. 

According to a World Health Organisation paper, “Filling extra vaccines in a vial is a common practice and is called overfill. It is to help health workers administer the correct number of doses to people.”

Typically, overfill accounts for: 

a) the leftover vaccine in a vial that cannot be extracted 

b) vaccine trapped in the space between the syringe and the needle - known as ‘dead space’ 

c) vaccine lost during adjustment if the dose is ejected into the air. 

Kerala has been able to greatly reduce its wastage, by precise extraction of vaccine from vial using low dead space syringes, say experts from the state.   

In Kerala's stock, each vial can offer 10 doses, but also has 0.58 to 0.62 ml (16 to 24%) of overfill. "It is possible to extract 11 to 12 doses (of 0.5 ml) from a 10-dose vial, if done skillfully. And in Kerala, many health workers have reported extracting 11-12 doses of vaccine from a vial, says Dr P Gopikumar, secretary of the Indian Medical Association (IMA). This is thanks to the training imparted to health care staff in the state.

The health department has made sure that only well-trained nursing staff are administering COVID-19 vaccine doses across the state, he adds.

Planning ahead 

Once opened, vaccine in a vial can only be used for up to four hours.

Residual vaccine from one vial CANNOT be mixed with vaccine from another vial and administered, says a WHO paper. Considering this, Kerala allots a set number of people for each vial during vaccination drives. 

“The health staff only opens vials when there are enough people to vaccine. This means that sometimes you send back people if the number is not met,” says Dr KP Aravaindan, pathology expert and member of the State Planning Board for COVID-19.

A vial in the state is opened only if 7-8 people can be vaccinated from it. Doctors and health workers also rigorously ensure zero wastage 

“The IMA along with the Health Department held a vaccination drive in Thrissur’s St Thomas college in April. On the last day,we had one vial left and just one person left to be vaccinated. This man had registered and arrived. But had we opened the vial, nine doses would have gone to waste. So we doctors went out and convinced people on the road who were not vaccinated to come to the centre and get inoculated. Finally, we managed to get 10 people and vaccinate them, with zero wastage,” Dr Gopikumar says. 

The Chief Minister in his tweet credited Kerala’s health care workers who have achieved little wastage. Prime Minister Modi too in a tweet lauded Kerala’s health workers for their feat. 

"Good to see our healthcare workers and nurses set an example in reducing vaccine wastage. Reducing vaccine wastage is important in strengthening the fight against COVID-19," the PM tweeted. 

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