The science behind Covid-19 vaccine boosters: Do we really need an extra shot?

‘The discussion took a new turn this week as fresh data backed up earlier findings - yet to be peer-reviewed - that the efficacy of both Pfizer's and Moderna's vaccines declines in a matter of months, and that one more dose of the Pfizer shot can reduce the rates of infections by 11 times and severe illness by 20 times in the elderly.

‘There are many arguments both for and against boosters, but what concerns policymakers and health professionals first and foremost is whether the science shows that they are a necessity. In considering this, we examine three key issues: Are immunity levels indeed dropping? Will extra shots really help and are they safe? What are the broader implications of giving another shot to those already vaccinated?’

Read here (Straits Times, Sept 19, 2021)

Considerations in boosting Covid-19 vaccine immune responses

‘In an expert review published September 13 online in the peer-reviewed journal The Lancet, a group of US and international scientists claim current evidence does not support providing booster doses of SARS-CoV-2 vaccines to the general public. The group—including 2 departing US FDA officials and WHO experts—said that any decision to provide additional vaccine doses should be evidence-based, concluding that despite a small drop in protection against symptomatic disease caused by the Delta variant, authorized vaccine regimens continue to provide high levels of protection against severe disease and hospitalization for all major SARS-CoV-2 variants. The authors acknowledged that some additional doses might be needed immediately for certain elderly and immunocompromised populations, but they encouraged prioritizing primary immunizations over booster shots for the general public.

‘The authors also acknowledged that booster doses might be necessary in the future due to waning immunity or the emergence of a vaccine-resistant variant but that current evidence does not warrant additional doses now because “efficacy against severe disease remains high.” The authors noted that currently available vaccine doses could save more lives and provide better protection against the emergence of new SARS-CoV-2 variants if used in previously unvaccinated populations, especially those in low- and middle-income countries.’

Read here (The Lancet, Sept 13, 2021)

How long does immunity last after Covid vaccination? Do we need booster shots? 2 immunology experts explain

‘As the rollout of COVID-19 vaccines continues, public attention is increasingly turning to booster shots, which aim to top up immunity if it wanes. But is a third dose needed? And if so, when? Let’s take a look at what the data tell us so far about how long immunity from COVID-19 vaccines might last.

• First, what about immunity following COVID-19 infection?
• How long does immunity from vaccines last?
• What about Delta?
• OK, so what now?

Read here (The Conversation, Aug 30, 2021)

Highly vaccinated Israel is seeing a dramatic surge in new Covid Cases. Here's why

‘Israel was the first country on Earth to fully vaccinate a majority of its citizens against COVID-19. Now it has one of the world's highest daily infection rates — an average of nearly 7,500 confirmed cases a day, double what it was two weeks ago. Nearly one in every 150 people in Israel today has the virus.

‘What happened, and what can be learned about the vaccine's impact on a highly vaccinated country? Here are six lessons learned — and one looming question for the future of the pandemic.’

1. Immunity from the vaccine dips over time.
2. The delta variant broke through the vaccine's waning protection.
3. If you get infected, being vaccinated helps.
4. Israel's high vaccination rate isn't high enough.
5. Vaccinations are key, but they are not enough.
6. Booster shots offer more protection — if you are one of the world's lucky few to get them.

Looming question: Will we need COVID-19 vaccines every several months? We don't know.

Read here (NPR, August 20, 2021)