COVID 19 – High vaccination is necessary but not enough to beat the Delta variant
Globally, governments' responses against Covid 19 pandemic are broadly in two camps: elimination strategy or endemic management approach. The highly infectious Delta variant (B1.617) are forcing policymakers to re-examine their countermeasures regardless of their chosen current response strategy. In 2021, both responses focus on achieving a high vaccination rate as the primary countermeasure against Delta. However, some experts have argued that while vaccination remains a key and essential layer of defense, on its own, it is insufficient and not a silver bullet. Why?
Vaccination – critical key defense but not a silver bullet
Vaccines three main purposes are:
- Reducing severe illness, hospitalization, and death
- Protection against infection (sterilizing immunity)
- Preventing transmission
Vaccination is a critical essential defense even against Delta because current vaccines remain effective in reducing severe illness resulting in hospitalization and death. Researchers from a Public Health England study<sup>1</sup> concluded that several vaccines after two doses remain highly effective against symptomatic disease from Delta.
What is also clear is with the arrival of Delta, the disproportionate adverse impact (hospitalization and death) for the unvaccinated. This has prompted governments to accelerate their rollout, including lowering the age of those eligible for vaccination. Countries like Israel and Denmark have already started vaccinating children from 12 years old. There is a discussion amongst experts of the need to approve vaccines for babies in early 2022.
Regarding vaccines' effectiveness in preventing getting infected, some early studies observe waning sterilizing immunity. Reports of breakthrough cases are worrying health experts and policymakers. Early studies of Delta breakthrough cases, for example, in Provincetown, Massachusetts2, have highlighted the risk of vaccinated population abandoning other public health countermeasures such as social distancing and wearing face masks.
Other early studies in Scotland3, the University of Oxford4, and from the USA5 have observed waning effectiveness and slightly lower level of protection in the months following vaccination against infection from Delta after two doses.
Consequently, Israel has introduced and expanded the rollout of booster shots for their population. Other countries like the U.K., the USA, Germany, and France have signaled similar booster shot campaigns. The booster shot campaign has divided experts and policymakers with a global shortage of vaccines, especially in developing countries. It has prompted the WHO to request a delay for a booster shot rollout, especially in wealthy countries.
The lower and waning effectiveness of current vaccines to prevent infection from Delta is a game- changer. What makes Delta so different from its predecessors?
Why is DELTA a game-changer?
Delta is a game-changer compared to other earlier versions of SARs CoV2 for the following reasons:
- Replicates faster in respiratory tracts
- Higher level (1,000 times) of viral load
- Become infectious earlier
- Longer viral shedding<sup>6</sup>
As a result, Delta can transmit earlier (4 days compared to 6) and transmit longer (18 days compared to 13 days). Consequently, some experts have concluded that Delta can transmit faster than the common cold and influenza and is as infectious as chickenpox and slightly less than measles.
Therefore, with Delta, as vaccination coverage increases, so will the raw numbers of breakthrough cases as seen in Israel, the U.K., and Iceland. Even though existing vaccines are still effective in preventing serious illness, the sheer number of infected cases can overwhelm any health system if the government continues to rely on existing countermeasures. Existing countermeasures needs revision. For example, the 14 days quarantine period may not be sufficient? But more importantly, there should also be greater focus and investment in new countermeasures such as treatments (pre, post-exposure, and therapeutic).
Delta's most important lesson for governments is the need for agility, deliberate exponential pace, and willingness to improve current countermeasures and introduce new ones.
An agile broad, integrated, multi-layer strategy, implemented with a deliberate exponential pace
Delta has exposed governments' linear, rigid, narrow strategies and glacial implementation. Ending this pandemic requires an agile broad, integrated, multi-layer strategy and implemented with deliberate and exponential pace. Being able to pivot with agility is essential, but an exponential pace is key to stay ahead of SARs CoV2.
A broad multi-layer strategy would have the following four layers of countermeasures would include:
Early detection & screening a. Innovative, comprehensive, and constant surveillance (including air ventilation) b. Robust testing approach to include rapid, less invasive, and faster reporting tests for different purposes c. Track and trace platform enabled by smart technology
Prevention & protection a. Vaccination – boosters, lowering eligible age, mix & match, vaccine passport, intranasal and oral vaccines b. Social distancing – for high-risk venues and events c. Face mask protocols for high-risk venues and events d. Personal hygiene e. Pre-exposure prophylaxis for essential workers
Treatments for exposed and confirmed cases a. Post-exposure prophylaxis for those exposed to close contacts b. Therapeutic (mild, moderate, and severe)
Caring for new arrivals and confirm cases a. Nuance isolation and quarantine arrangements for new arrivals b. Home, community, and hospital care for positive cases
Governments are trying to get the right balance between going too early or late, too fast or slow, too much or little. Part of the challenge is "waiting for more evidence" before taking action. The key challenge for most governments is agility in change and implementation.
Perhaps a bigger problem is the glacial timeframe to take action even when the evidence is clear. In 2021, there are more testing and treatment options compared to the early days of the pandemic in 2020. When it comes to testing, apart from the RT-PCR test, other types of rapid, less invasive, faster results reporting and point of care antigen tests should be part of the testing toolkit. In the case of better treatment, several countries7 has approved monoclonal antibody therapy to treat mild symptoms in the early stages of infection and post-exposure prophylactic treatment.
There is still a real fear, stigma, and mental stress for someone with Covid 19. Being able to be tested quickly and getting results back faster so that early treatment can commence can make a positive difference to the physical and mental well-being of Covid 19 patients. Equally, it can go a long way to alleviate the disproportionate “feardemic” in the general community.
Agility also requires developing and trialing alternatives rather than just doing more of the same faster. For example, to prevent hospitals from being overwhelmed, some countries like Singapore are setting up community care centers to care for people with mild and moderate symptoms that cannot be cared for at home. Not Covid 19 case which is unwell needs to be hospitalized. Hospitals should be for severely unwell patients requiring specialized skill, equipment, complex and invasive therapy (ICU and ventilator support). Step down community care centers closer to where patients live is an innovation implemented in countries like Singapore. Likewise, models for recovery at home will complement community care centers. Such a hub-and-spoke approach is not new to the health system. It just needs to be part of the broader care system rather than just sending all unwell cases to hospitals.
Final word
Delta is a formidable opponent that needs to be respected rather than feared. Delta can be beaten and brought under control provided governments implement a broad integrated multi-layered response strategy with deliberate exponential pace and agility. Vaccination is a key part of the prevention and protection layer, and governments globally are rushing to lift their vaccination coverage. There is still more to be done in the early detection, screening, prevention, and protection layers. However, greater focus and attention need to go the treatments and caring options for those infected.
Our decision-makers are facing a tough and challenging time, but there is no room for complacency and mediocre performance. Getting on top of Delta requires more than just doing more of the same. Second, agility and pace to adopt, adapt and implement a broad and integrated strategy that matches the evolving rhythm of SARs CoV2 virus. We should learn fast and fail fast where necessary because there is plenty of viruses out there, and no one wants to be caught with our pants down as we did with SARs CoV2.
CHUAH Jin Chai 蔡 仁材 Wellington, NEW ZEALAND 31st August 2021
Notes 1. https://www.gov.uk/government/news/vaccines-highly-effective-against-b-1-617-2-variant-after-2-doses 2. https://www.cdc.gov/mmwr/volumes/70/wr/mm7031e2.htm 3. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)01358-1/fulltext 4. https://www.ndm.ox.ac.uk/files/coronavirus/covid-19-infection-survey/finalfinalcombinedve20210816.pdf 5. https://www.cdc.gov/mmwr/volumes/70/wr/mm7034e4.htm?s_cid=mm7034e4_w 6. https://www.ucsf.edu/news/2021/08/421171/how-dangerous-delta-variant-heres-what-science-says 7. https://www.youtube.com/watch?v=zvRF4HrXHaA