The science behind city’s five-point Covid strategy
Declaring a war on the coronavirus disease (Covid-19), armed with hospital beds, testing kits, pulse oximeters, oxygen concentrators, and surveyors with pens and notebooks, may sound laughable on the face of it, but in the absence of a vaccine or cure, these are the most effective tools to save lives and stop the spread of a virus that has infected 529,485 and killed 16,101 in India.
Fortunately for us, these work when used in combination with self-protection measures, such as frequent handwashing, wearing a mask, and social distancing of at least two metres in public places.
Here’s why these five weapons are part of Delhi chief minister Arvind Kejriwal’s arsenal.
BEDS
Around 22% of Covid-19 deaths in Delhi occur within 24 hours of hospital admission, and another 40% within 48 hours of admission, which indicates that people are seeking treatment in severe or critical disease stages, when treatment options are limited.
The Union health ministry on Saturday asked the Delhi government to analyse data for all Covid-19 deaths to find out why people were reaching hospitals too late for treatment, which was happening for many reasons, including delays in admission because of bed shortages, fear of infection, and poor disease assessment, among others.
To ensure everyone who needs treatment get it, Delhi now has 13,335 Covid beds, and plans to add another 1,000 next week in a field hospital in Dhaula Kuan run by army doctors and paramedics.
Patients with moderate disease can be treated with a battery of newly approved treatments, including the antivirals remdesivir and favipiravir, the steroids dexamethasone and glucocorticoids, and convalescent plasma therapy, which is an experimental therapy available at some hospitals.
TESTING KITS
Delhi has ramped up testing from around 5,000 tests two weeks ago to over 21,000 tests a day, with the state government adding rapid antigen testing to conventional reverse transcriptase-polymerase chain reaction ( RT-PCR) tests for quicker results. It has placed orders for 600,000 rapid antigen tests to top up the 50,000 kits it had acquired from the Centre.
“Testing and isolation stops disease transmission and protects those around us from infection. Asymptomatic, presymptomatic people and those with mild disease can also infect and sicken others, which can only be prevented by widening testing so that people are aware of their positive status and take measures to stop infecting others,” said Dr Dileep Mavalankar, director of the Indian Institute of Public Health, Gandhinagar.
PULSE OXIMETERS AND OXYGEN CONCENTRATORS
A key clinical sign of Covid-19 is extremely low blood oxygen level, which can lead to hypoxia or death from oxygen starvation.
The healthy range of SPO2 (peripheral oxygen saturation) is between 95% and 100%, but in people with Covid-19, it may fall below 90% without inducing symptoms of breathless, chest discomfort, lethargy or confusion.
This condition, called “silent” hypoxia, results in people not realising they are oxygen-starved till their lungs collapse.
Doctors recommend that the moment symptoms begin, oxygen levels must be checked frequently with a pulse oximeter, which is a small device that measures SPO2 at the finger tip.
Low oxygen levels are a red flag for hospitalisation, where oxygen support can help save lives.
“Higher SPO2 levels after oxygen supplementation were associated with reduced Covid-19 mortality independently of age and sex,” according to study published in Mayo Clinic Proceedings in June.
“Pulse oximeter is working as a security cover for Covid-19 patients. It helps them check oxygen levels at frequent levels and alert us if there’s anything serious…,” Kejriwal said on Saturday.
CONVALESCENT PLASMA THERAPY
“Plasma therapy is being used by many now. This doesn’t work for patients who are on ventilators or who have multiorgan failure but helps those with moderate symptoms,” said Kejriwal. The chief minister is partly right. Plasma therapy is recommended for patients with moderate disease but its effectiveness is still under review, which makes this experimental therapy “hopeful but unproven” at best.
Plasma from the blood of a recovered patient, which carries specific antibodies that can neutralise the new coronavirus, are transfused into a sick Covid-19 patient to reinforce the immune system. Convalescent plasma has been used to prevent and treat infections since the 1890s, and immunoglobulin IGE serum is still injected in people with animal bites to prevent rabies, and varicella-zoster immunoglobulin is given to pregnant women who have been exposed to chickenpox, to prevent pregnancy complications. The therapy has no serious adverse reactions, but scientists say there is need for larger randomised-controlled clinical trials to establish efficacy.
SURVEYS, SCREENING
Identifying undiagnosed infection in people who may have missed getting tested because they were asymptomatic, had mild symptoms, or testing wasn’t accessible, helps to calculate the real number of people affected. “People with mild illness go out and spread infection, so even asymptomatic and pre-symptomatic close contacts of a positive case must quarantine themselves even if you don’t feel ill. If you don’t, you become part of the chain and transmission doesn’t stop,” said Dr Randeep Guleria, director, All India Institute of Medical Sciences Delhi.