3 tests crucial for containing transmission

The government should incorporate antibody and antigen tests alongside the PCR tests for Covid-19 to elevate screening capacity that is crucial to contain the virus transmission, said experts.

The government approved only PCR tests until now, but the number of tests being conducted -- around 8,000 to 10,000 a day -- is very small compared to the required testing facilities for the population of 17 crores, they said.

They also said that both the PCR and the antibody tests have some limitations, but now is the time to use both types of kits.

The recommendations came from a virtual seminar organised by Gonoshasthaya Kendra yesterday.

Prof Muzaherul Haque, former advisor to the World Health Organization, said, "We don't know the actual number of people infected by Covid-19 because the rate of test is very low here. We cannot devise an effective strategy based on this rate of tests."

Therefore, antibody and antigen tests should also be approved, apart from the PRC tests, he said, adding that antibody is developed in body a few days after infection, while antigen can be detected from the day one of infection of Covid-19.

The accuracy level of PCR test depends on the efficiency of swab collection from throat and nose. Its false positive of false negative can be between 30 and 40 percent, Prof Muzaherul further said.

"Our health system has a huge management problem. Are we prepared if 12 crore people of the country are infected and five percent of them are to go through hospital treatment?" he asked.

Prof Muzaherul raised the question at a time when 386 people died of coronavirus and the number of total infection was 26,738.

Meanwhile, a team of Gonoshasthaya Kendra, led by Dr Bijon Kumar Sil, developed Rapid Dot Blot kit that can test both antibody in blood and antigen in saliva.

Gonoshasthaya Kendra applied for registration of the kit in mid-March, but has yet to get approval for mass production. The kit is now going through performance trial at the Bangabandhsu Sheikh Mujib Medical University (BSMMU).

At the seminar yesterday, Dr Bijon said no single test should be considered gold standard. Authorities should go for both antibody and antigen tests.

"The new coronavirus can last in saliva longer than that in droplets of sneezing. If saliva is left on the soil, it dries and then the virus can mix into the air," he said, adding that they have found good result by antigen test in saliva.

Dr AK Azad Chowdhury, a noted bio-chemist and former vice chancellor of Dhaka University, said if anybody is found negative in antibody test, a PCR test can be conducted on him for a comprehensive result.

Antibody and antigen tests may not be 100 percent accurate, but large-scale and quick tests are possible through this, he said.

Prof Kamrul Hasan Khan, former vice chancellor of BSMMU, congratulated Dr Bijon Kumar Sil for developing the Rapid Dot Blot, and added that there was nothing to make controversy out of it.

The kit is now undergoing trial at BSMMU, and if it is found successful, it will be fine, he said.

However, so far antibody tests are being used mainly for surveillance on population who developed immunity, not for diagnosis.

On the other hand, antigen test is yet to be used by any developed country and that there should be caution about its use.

He also said Gonoshasthay's way of dealing with the drug administration and blaming it for delay in approving the kit was not appropriate. Approving a kit has a rule that should be followed, he added.

Gonoshasthaya Kendra Founder and Trustee Dr Zafrullah Chowdhury said it is an emergency situation and the countries like USA and UK are issuing emergency authorisation of drugs, kits and vaccines.

"We should go for antibody and antigen tests alongside PCR tests for the sake of saving our people, our economy. We would also request BSMMU to complete the test before the Eid holiday begins because infection is going up every day and it's an emergency," he said.