**12. Testing variants against serum**

Researchers and physicians have also explored different components of blood for imparting immunity to the Covid-19 affected patients. Serum, a component of blood that contains antibodies was taken from a vaccinated individual and combined with the virus in the lab, to see if antibodies contained in the serum block virus from infecting cells [82, 83]. There is currently no centralized system for testing all different vaccine sera against all different variants. Most studies have been small, and have primarily focused on mRNA vaccines [82, 84]. B.1.1.7 variant was first detected in the UK; and the B.1.351 variant was detected in South Africa, where serum testing showed a reduction of about six-fold in antibody sensitivity [85]. The other variants of concern currently identified by the CDC are P.1, which was first detected in travelers from Brazil, and two variants first detected in California B.1.427 and B.1.429 [85, 86]. Fewer studies are available on these variants, but current data indicate that the reduction in antibody sensitivity is somewhere between B.1.1.7 and B.1.351 [85]. Overall researchers need more laboratory data. But even when larger studies become available on all different variants and vaccine sera, these data may prove inconclusive [83]. Testing against serum samples has limitations. A big one is that antibodies are only one part of the immune response. In serum, the patient will not have our T cells, the patient will not even have our memory B cells or plasma cells that might be important just for antibody response [87, 88]. So, a lot is missing and that makes it hard to determine how a decrease in antibody sensitivity of 6 fold, in the lab, translates to vaccine effectiveness in the real world [86, 89]. Given these limitations to laboratory testing, it is of paramount importance to collect data on the ground. One example of such data would be sequencing variants infecting people, who become seriously ill with COVID-19 despite being vaccinated [84]. Another source of ground data is ongoing and recently completed vaccine clinical trials. ChAdOx1 nCoV-19 derived vaccine did not fare well in South Africa, where B.1.351 variant dominated, and South Africa halted its distribution in February [89, 90]. ChAdOx1 nCoV-19 derived vaccine is close to filling for authorization in the US and this vaccine is already being distributed elsewhere, including in the UK, and Europe by WHO [89]. Another vaccine that was tested in South Africa is from protein subunit vaccine, this vaccine is not yet being distributed, but it is getting close to filling for authorization in the UK, the US, and elsewhere. The most recent update read out of data suggests that while the protein subunit vaccine was almost 90% effective in the UK, it was much less effective in South Africa about 49 or 55% depending on whether or not people include participants infected with HIV [74, 90, 91]. A vaccine made by a piece of a modified virus is now being distributed in the US, reports a similar trend. This vaccine was 72% effective at preventing moderate to severe disease in US 28 days after vaccination. In South Africa, that number was only 64% [90]. But importantly this vaccine's efficacy against the severe disease was similarly high across regions [74, 84]. The currently available data indicate that while variants do pose a real threat to vaccine effectiveness, the available vaccines remain potent tools in fighting the pandemic. But researchers and public health experts also stress, that there will be more SARS- CoV-2 variants [92]. This underscores the importance of a global approach to surveillance, tracking, and vaccine development. But CDC Director Dr. Rochelle Walensky has emphasized the need to scale up surveillance across the US. In early January 2021, there were 250 samples a week that were being sequenced. In addition, CDC, NIH, vaccine procedures, and other groups are already discussing and collecting data on various vaccine strategies for combatting variants [92]. One potential strategy is a booster shot that would expose the human body to viral spike protein from the newer, resistant variant. This would stimulate the immune system to produce antibodies specific to the new variant in addition to an extra protective cushion for protection

### *Perspective Chapter: Tracking Trails of SARS CoV-2 – Variants to Therapy DOI: http://dx.doi.org/10.5772/intechopen.106472*

against other variants as well [88, 93, 94]. Studies evaluating both booster approaches have already started. Other strategies may also be like a bivalent vaccine, which induces an immune response to two different antigens with one shot. Such a vaccine could induce immunity to two different variants or two viral proteins from the same variant [79, 95]. But while such strategies are important to evaluate, the most significant way to mitigate the threat posed by variants is to reduce the community spread of SARS CoV-2. The way to decrease the amount of virus circulating is to get as many people vaccinated as possible, as quickly as possible, and to continue preventive measures like mask wearing and physical distancing [84, 95].
