Higher vaccination rates go hand in hand with lower oxygen demand

NEW DELHI, May 19
India’s second wave of Covid-19 has been marked by a grave oxygen crisis. More than 500 patients have died just in hospitals because of a shortage of the life-saving gas. Some of these deaths could have been prevented had the country vaccinated its people at a faster clip, data suggests.
On the evening of May 14, the oxygen crisis reached Imphal, Manipur, where a leading private hospital suspended admission of new patients because it had run out of medical oxygen amid a Covid-19 surge in the State.
At the time, the official caseload in the State with a population of 31 lakh was just over 5,500 cases. Its overall oxygen requirement that evening, according to the State’s Health Secretary V Vumlunmang, was nearly 900 D-type cylinders.
Not too far away, Tripura, a considerably more populated State with 40 lakh people, was reporting fewer Covid-19 cases at 4,230. Strikingly, its oxygen requirement was in the range of just 100-115 D-type cylinders.
In other words, Manipur’s need for oxygen was more than eight times that of Tripura, despite its caseload being only 27 % higher.
What explains this?
Tripura’s high vaccination coverage, according to its State officials.
“Currently, we have 45-50 people who need oxygen,” said Dr Siddharth Shiv Jaiswal, who heads the State’s National Health Mission. “Tripura’s oxygen requirement is much less than neighbouring States. That is because we have vaccinated a large percentage of our population. That is proving beneficial to the State now.”
Indeed, Tripura’s vaccination rate is much higher than most other States in the North East. As of May 16, the State has administered one dose of the vaccine to nearly 90% people in both the age groups above 45 years and 60 years.
On the other hand, Manipur has managed to inoculate barely 30% people in the 45-plus and 60-plus age groups with at least one dose.
Consider Meghalaya which has a population of 32.2 lakh and caseload of nearly 4,500. The State’s daily oxygen requirement hovers between 6.5-8 metric tonnes, said Ram Kumar, Director of Meghalaya’s National Health Mission. That is around 800 D-type cylinders–comparable to Manipur.
In terms of vaccination coverage as well, the two States are similar. Meghalaya has administered the first dose of the vaccine to 30% of its population in the 45-plus category and 25% in the 60-plus category.
The Indian Government does not release data concerning daily oxygen requirements of States. However, on April 29, the Centre furnished this information in an affidavit to the Supreme Court. An analysis of that dataset by Scroll.in suggests this correlation broadly holds for States even outside the North East: the higher the vaccination rates, the lower the demand for medical oxygen in States with comparable caseloads.
The case of larger States
On April 28, the day for which the Centre revealed State-wise oxygen demand in the affidavit, Andhra Pradesh, Chhattisgarh and West Bengal had comparable Covid-19 caseloads. Andhra’s reported caseload was 1.07 lakh; Chhattisgarh’s 1.15 lakh; and West Bengal’s 1.05 lakh.
However, there was a vast difference in their oxygen requirements: Andhra wanted 480 metric tonnes, West Bengal 308 metric tonnes, while Chhattisgarh had a considerably lower demand at 227 metric tonnes.
Even Rajasthan with a much higher case load of 1.63 lakh had oxygen requirements less than Andhra Pradesh and West Bengal at 265 metric tonnes.
On the vaccination front, Andhra Pradesh and West Bengal have been laggards while Chhattisgarh and Rajasthan are two of the best-performing bigger States.
As of Sunday evening, Andhra has vaccinated around 30% of its 60-plus and 45-plus population with at least one dose. West Bengal’s corresponding numbers were less than 35% and 28% in the respective age groups.
Chhattisgarh boasts of a much higher number: It has vaccinated around 67% people in both the age groups. Rajasthan, for its part, has vaccinated nearly 80% of its 60-plus population and 61% of its 45 plus population.
A Rajasthan State official said that there had been few reported instances of vaccinated people requiring oxygen support. “To the best of my knowledge, negligible people who received two doses reached the stage of complication,” said Dr Praveen Aswal, the State’s nodal officer in the Integrated Disease Surveillance Program. “Single dose also gives protection–I think this is a Nation-wide phenomenon.”
In Chhattisgarh, Samir Garg, Executive Director at the State’s Health Resource Centre, said a correlation was “likely”. “I manage a large community health workers’ program,” he said. “Most of them by virtue of being healthcare workers got vaccinated with both doses well before the second wave hit. They are still getting positive but hardly anyone is getting seriously ill.”
Garg, however, cautioned that there needed to be “more systematic” studies to establish the correlation between vaccination and oxygen requirement, if at all. “Oxygen demand is not standardised in the way it is calculated in all the States,” he said. “If a State does not have enough hospitals, there would be fewer people admitted in hospitals and hence your demand would not be that much.”
The formula for calculating oxygen demand
The Government of India has a theoretical formula to calculate oxygen demand that it detailed in its affidavit on April 29. An empowered group of medical experts, the Centre stated, had concluded that 80% of all Covid-19 cases in India were mild and did not need oxygen. Of the rest, 17% needed hospitalisation, of which 50% required oxygen support. The remaining 3% needed ICU beds.
However, the final allocation was based not on the formula but on “demand from the States”, the Centre said.
To be sure, the demands of the State as stated in the affidavit reflect that it was not necessarily calculated adhering to the Centre’s formula–an indication that the requirements reflect the varying disease burden on the ground.
Exceptions
The table of requirements in the affidavit does throw up exceptions vis-à-vis vaccination coverage and oxygen requirements. The two most prominent anomalies are Gujarat and Kerala. Gujarat’s oxygen requirement of 1,000 metric tonnes on April 28 was monumentally higher than States with similar caseloads and lower vaccination coverage.
At the other end of the spectrum, Kerala’s requirement of 99 metric tonnes was minuscule compared to its caseload of 2.66 lakh and middle-of-the-table vaccination rates. (For context: Gujarat’s caseload at the time was half with 1.33 lakh cases, and its vaccination numbers have consistently been better, albeit marginally, than Kerala).
This, as many experts have pointed out on different occasions, could just be a case of inefficient clinical management more than anything else with patients being administered oxygen through high-flow nasal cannulas instead of non-invasive ventilators. The former consumes more oxygen and may be unnecessary in moderate cases.
Health officials in Kerala said their low requirements were a result of optimal usage. “We just give enough oxygen to maintain levels somewhere between 94-95, we need not go right up to 98-99,” said Dr Amar Fettle, State nodal officer for Covid-19 . “So we use very low flow of 2 to 4-5 litres per minute to ensure that the patient may be maintained in a safe environment.”
Fettle said his clinical experience seemed to suggest that vaccinations did indeed reduce need for critical care. “Of those vaccinated, maybe 10% need hospitalisation and out of that 10% may need ICU support or oxygen,” he said.
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