ShareWASHINGTON: The efficacy of third doses of the Pfizer and Moderna mRNA vaccines wanes substantially by the fourth month after administration, a new study by the US Centers of Disease Control and Prevention (CDC) said Friday. Though it's now well documented that vaccine efficacy goes down after two doses, relatively little has been published on the duration of protection after a booster.
The new study was based on more than 241,204 visits to the emergency department or an urgent care clinic, and 93,408 hospitalizations, which are more serious, among adults with COVID-19-like illness during Aug 26, 2021-Jan 22, 2022. Vaccine efficacy was estimated by comparing the odds of a positive COVID test between vaccinated and unvaccinated patients and using statistical methods to control for calendar week, geographic area, while adjusting for age, the level of local transmission, and patient characteristics like comorbidities.
During the Omicron-predominant period, vaccine efficacy against COVID-associated emergency department or urgent care visits was 87 percent during the two months after a third dose, but fell to 66 percent by the fourth month. Vaccine efficacy against hospitalization was 91 percent in the first two months, but fell to 78 percent by the fourth month after a third dose.
"The finding that protection conferred by mRNA vaccines waned in the months after receipt of a third vaccine dose reinforces the importance of further consideration of additional doses to sustain or improve protection," the authors concluded. Speaking at a White House COVID briefing on Wednesday, President Joe Biden's top medical advisor Anthony Fauci said it was likely that fourth doses would more likely be needed for subsets of people who mount weaker immune responses, such as the elderly and immunocompromised.
In a separate development Friday, the Food and Drug Administration (FDA) authorized a new lab-grown antibody treatment by pharmaceutical company Lilly called bebtelovimab. The drug is administered as an intravenous injection over at least 30 seconds and has been green lighted for the treatment of mild-to-moderate COVID among people 12 and over at high risk of severe disease. Data supporting the authorization came from a clinical trial that showed the drug has strong promise against Omicron. Lilly's previous antibody treatment was de-authorized by the FDA after it was found to be ineffective against this variant.
Meanwhile, the World Health Organization said Friday that it had prequalified the arthritis treatment tocilizumab for use in patients hospitalized with severe COVID-19, in a bid to increase access to the pricey drug. The monoclonal antibody, used in anti-inflammatory drugs made by Swiss pharma giant Roche, has been shown to reduce the risk of death and also hospitalization time in certain patients suffering from severe COVID.
WHO has, like the United States and the European Union, already recommended its use to treat severe COVID in hospital settings. But it remains in short supply and is very expensive - a single dose reportedly goes for up to $600 in lower-income countries, WHO said, adding though that its prequalification should help make it more accessible. The UN health agency said it had added three different compositions of the monoclonal antibody to its list of prequalified treatments for the pandemic disease, in a move aimed to spur more the production of more cheaper generic versions.
WHO told AFP its prequalification process was primarily aimed at ensuring the quality, safety and efficacy of medical products procured to developing countries. A prequalification provides assurances to countries that they are purchasing quality health products. Prior to tocilizumab, the WHO has prequalified three different compositions for the steroid dexamethasone for treating COVID, as well as Gilead's antiviral remdesivir, although that prequalification has since been suspended.
Tocilizumab has previously been authorized mostly for the treatment of arthritis in about 120 countries. But during the pandemic, it has also been shown to suppress a dangerous "cytokine storm" - the over-reaction of the immune system to the coronavirus. WHO pointed out that the patent for tocilizumab had expired for most uses. This, it said, "means there should be no intellectual property barriers," although it warned there was "low global availability for quality-assured biosimilars of the product".
Also, the head of the WHO said Friday the acute phase of the pandemic could end this year, if around 70 percent of the world gets vaccinated. "Our expectation is that the acute phase of this pandemic will end this year, of course with one condition, the 70 percent vaccination (target is achieved) by mid this year around June, July," Tedros Adhanom Ghebreyesus told reporters in South Africa. "If that is to be done, the acute phase can really end, and that is what we are expecting. It's in our hands. It's not a matter of chance. It's a matter of choice."
He was speaking during a visit to Afrigen Biologics and Vaccines, which has produced the first mRNA COVID vaccine made in Africa using Moderna's sequence. "We expect this vaccine to be more suited to the contexts in which it will be used, with fewer storage constraints and at a lower price," said the WHO boss. The vaccine will be ready for clinical trials in November, with approval expected in 2024.
Afrigen is leading the pilot project, backed by the WHO and the COVAX initiative. Set up in July, the tech transfer hub will train other countries and hand out production licenses to poor nations left out in the race for the life-saving shots. Tedros said WHO was "committed to supporting the development of local manufacturing in Africa and around the world, to increase regional health security".
Just over 11 percent of Africans are vaccinated, the lowest rate in the world. Last week the WHO's Africa office said the continent must boost its vaccination rate "six times" to reach the 70 percent target. South Africa and India have since Oct 2020 led calls for waivers on vaccine patents, or intellectual property rights, on COVID-19 vaccines saying this would help spur local production.
But a number of wealthy countries hosting large pharmaceutical companies have opposed the move, which believe that would discourage innovation. World Trade Organization, however, announced last month that an accord between rich nations and developing countries on the IP waivers could be just weeks away. - Agencies
