*Do I still need to get a COVID vaccine if I’ve had coronavirus?

 The COVID vaccine rollout is underway, with Australians lining up to get their jabs. But what if you have already had COVID-19? Is it still a good idea to get vaccinated?

March 25, 2021 5.51am AEDT

Cassandra Berry, Murdoch University

People who have had COVID will still benefit from having a COVID vaccine. Here's why.

Although natural exposure to the virus stimulates immunity, we don’t yet know how long this immunity will last. And people will vary in their ability to mount a protective immune response.

Even if you’ve had COVID-19, you should still get vaccinated. A COVID vaccine may offer more reliable and sustained immunity than a previous infection. At the very least, it will add an extra layer of targeted protection.

Here’s how our immune response works after a natural infection versus a vaccine.

From B cells to neutralising antibodies

Soon after becoming infected with SARS-CoV-2 (the virus that causes COVID-19), our immune cells (T cells and B cells) activate. Activated B cells produce so-called neutralising antibodies. These antibody-secreting cells defend our bodies against the infection by making antibodies that bind to spikes on the virus surface, and block the virus from entering our cells.

Neutralising antibodies spill over into the bloodstream and travel around the body looking to mop up virus. After the infection has resolved, these activated B cells calm down and transition to a resting state. They move from our blood to our lymph nodes and bones. These so-called memory B cells survive for decades, along with help from memory T cells.

But they need a nudge once in a while to ensure they’re ready to kick into gear if we’re exposed to an infection.

SARS-CoV-2 viral particles have surface spikes (in green), to which antibodies attach. NIAID/flickr

Our immune cells rely on memory

When we’re re-exposed to a virus, or receive a vaccine booster, these memory cells awaken, become activated and produce large amounts of antibodies much faster. This immune memory reduces the risk we’ll become infected with SARS-CoV-2. But if we do, it allows for quicker healing from COVID-19.

Sustained neutralising antibody levels indicate a good degree of protection against SARS-CoV-2. How long we hang onto natural immunity after COVID-19 is variable and depends on viral, human and environmental factors. For example, the viral variant can make a difference, along with our genes, underlying health conditions, and age.

These factors can affect our neutralising antibody levels, which can wane over time to dip below protective levels.

As COVID-19 hasn’t been around for a particularly long time, it’s difficult to know how long natural immunity generally lasts. However, antibodies and immune memory appear to last for at least two months.

For patients who have recovered from SARS, a related coronavirus, research has shown they maintained antibodies for up to two to three years following infection.

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Read more: The second phase of Australia's COVID vaccine rollout is underway, despite a rocky start. Here's what you need to know

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Immune responses to a vaccine

Again, because of the short time frame, we have limited data on sustained antibody responses following vaccination. But immunity appears to be strong three months after the Oxford/AstraZeneca vaccine.

With COVID-19 vaccines, certain variable factors have been targeted, in a way they can’t with natural infections. For example, considerations like the dose size and the time between doses are all established to confer optimal immunity.

As we continue to monitor people who have received the COVID vaccines, we’ll develop a better understanding of protective immunity and its longevity.

Staying on top of variants

Natural immunity from infection may protect against other variants to some degree, but vaccines will play a crucial role as the virus continues to mutate.

It may be necessary to get regular boosters of the COVID vaccine until the pandemic is under control. This will provide protection against variants our pre-existing antibodies may not be able to neutralise.

Boosters enhance our broad immunity to parts of the spike proteins shared between different virus variants. Antibodies produced to these common regions can neutralise the virus and stop infection.

We saw this to a limited extent in people who had common cold infections with other coronaviruses before COVID-19.

Boris Johnson, who was in intensive care with COVID last year, received the first dose of his COVID vaccine recently. Frank Augstein/AP

Only one jab? Vaccines as a cure for long COVID?

There’s been some research suggesting people who have had COVID may only need one dose of the vaccine to be protected.

For people who have had COVID, one dose may serve to top up their antibodies to protective levels. This is because they’re starting on a stronger footing in terms of their antibody levels and immune memory, compared to people who haven’t had the virus.

But experts in Australia still recommended two doses, regardless of whether you’ve had COVID.

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Read more: Why we'll get COVID booster vaccines quickly and how we know they're safe

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Meanwhile, reports have indicated people experiencing long COVID may also benefit from vaccination. We’re not sure how this happens, but symptoms may improve with clearance of any hidden virus reservoirs from the body. Research into this phenomenon is ongoing.

At the end of the day, when the vaccine is available to you, you should get vaccinated, even if you’ve had COVID-19. While the vaccine is likely to protect you, it’s also important to protect others, as we look towards a goal of herd immunity.

CoronavirusImmune responseneutralising antibodiesCOVID-19COVID vaccinesImmune memory

https://theconversation.com/do-i-still-need-to-get-a-covid-vaccine-if-ive-had-coronavirus-157599

Coronavirus: how will the vaccine advances of 2020 alter the pandemic path in 2021?

 

• The extreme lows brought by Covid-19 have sparked unprecedented speed in developing and approving vaccines and rolling them out
• A number of factors beyond the shots themselves will determine if and how transmissions are curbed

Josephine Ma

Published: 7:00am, 8 Jan, 2021

Illustration: Sierra Chiao

This is the latest story in 

our series on the Covid-19 pandemic

, a year after the first cases were reported in the mainland Chinese city of Wuhan. It explores how vaccines have advanced at unprecedented speed and what prospects they hold for the fight against the disease this year. Please 

support us

 in our mission to bring you quality journalism.

One year after a 

novel coronavirus

 caused the worst pandemic in a century, several vaccines have already been rolled out and others are expected to follow in the coming months.

It is a record. Before this, no vaccine had been developed in less than four years, sometimes taking decades.

The year 2020 was catastrophic for many people, but it was also a record-setting year in terms of vaccine research. Now the big question is: how will 

Covid-19 vaccines

 make a difference in 2021?

How history was made in 2020

The genome sequence of the new coronavirus was shared on a public platform on January 11, 2020, and thanks to the tireless work of the team led by Shanghai-based virologist 

Zhang Yongzhen

, scientists in various countries began to work on vaccines.

For example, on January 13 last year, US company Moderna and the National Institutes of Health had already finalised the sequence for an mRNA vaccine against the new virus and they soon began to make a clinical batch.

Oxford University also moved quickly to adapt its research on a Middle East respiratory syndrome vaccine using a chimpanzee virus as a vector to express Sars-CoV-2, the official name of the new coronavirus.

Despite the sprints made by vaccine developers, when 

World Health Organization

 (WHO) chief Tedros Adhanom Ghebreyesus said in February that a vaccine might be ready in 18 months, it appeared unrealistically ambitious because there had never been a successful vaccine against a coronavirus.

“If you asked in February and March [2020] whether we have a vaccine available in December, nobody would have said that is going to happen that quickly,” said John Moore, professor of microbiology and immunology at Weill Cornell Medical College in New York.

But scientific research in vaccines over the past decade laid the groundwork.

“You have to remember the programme did not start from nothing,” Moore said.

Inside China’s exhausting race to develop a coronavirus vaccine

5 Jan 2021

For example, even though there has never been an mRNA vaccine for humans, there has been research into the technology for about 10 years, including laboratory and early clinical tests to determine whether it might work to tackle diseases such as Ebola, Zika, influenza and cancer.

In the past, developers needed to make sure the vaccines worked before they could start manufacturing. But now, massive government funding allowed them to invest in manufacturing facilities before they had to prove the vaccines worked.

The 

Warp Speed programme

 under the administration of US President Donald Trump gave more than US$12 billion to vaccine makers such as 

Moderna

, AstraZeneca, Johnson & Johnson, Sanofi and Novavax. In return, the US government signed contracts with these companies so it could meet its goal of securing 300 million doses for Americans.

The vectored vaccine by Oxford-AstraZeneca has an efficacy rate of at least 70 per cent. Photo: Reuters

In contrast, the Chinese government set up a special task force in January to fund and coordinate vaccine and drug research after the Wuhan outbreak. By April, it had identified five different types of vaccine technologies it would pursue for the vaccine race, including the traditional 

inactivated vaccine technology

 that has long been shunned by the West.

“There are a couple of reasons that inactivated vaccines are not really pursued in the West. One, is it is an old technology and pharmaceutical companies have moved on to more modern methods,” Moore said.

“The second is that there is always a risk, going back decades ago, of not inactivating vaccines thoroughly enough and leaving some virus around,” he added, referring to an accident in the US in 1955 related to polio vaccines.

China’s diplomacy leans on vaccine outreach but beware soft power failure

5 Jan 2021

He said there was no longer a culture facility in the US suited to making – and inactivating – large amounts of live virus.

China’s approach, however, is paying off. China was never a global leader in vaccine research but it has emerged as a front runner in the Covid-19 vaccine race. This is despite not being the first country to cross the finishing line, hampered by too few local cases for efficacy analysis and forced to host the final phase of vaccine trials in other countries.

Trial and regulatory review procedures were compressed and held simultaneously to speed up the process, which analysts said could be an example for future research.

Stanley Plotkin, who invented the rubella vaccine in the 1960s and was an important player in the vaccine industry for decades, said the scientific events of last year were unprecedented and would change the playbook for vaccine research.

“Never before have so many developers … worked on a single vaccine using so many different platforms in so short a time. Yes, it will help in the future,” Plotkin said.

But the surprisingly fast progress also depends on a bit of luck, as the virus turns out to be less tricky than some other pathogens for vaccine development.

Most of the 63 vaccines now undergoing clinical trials target the spike protein of the coronavirus that binds to human cells. The target, which was identified based on past vaccine research for coronaviruses, turned out to be the right one.

John Moore said: “HIV, for example, is much harder to vaccinate against … Influenza is much harder to deal with than Sars-CoV-2. So Sars-CoV-2 looks like it is quite easy compared to some pathogens. It has the side of vulnerability that can be exploited – that does not apply as much to other viruses.”

What should we expect in 2021?

Uncertainties remain about whether and when the vaccines can bring an end to the pandemic, which infected over 87 million and killed at least 1.8 million people in roughly one year.

Efficacy data from the front-running vaccines are all far better than the benchmark of 50 per cent set by the WHO and regulators in many countries.

The two mRNA vaccines developed by Pfizer-BioNTech and Moderna achieved about 95 per cent respectively. The vectored vaccine by Oxford-AstraZeneca had an efficacy rate of at least 70 per cent, although it could be even higher after adjusting the dosing.

China says it can produce 1 billion doses of Sinopharm vaccine this year

6 Jan 2021

China also announced one of its inactivated vaccines had an efficacy of 79 per cent. The country gave conditional approval to the vaccine for market launch on December 31 and promised to offer free inoculations to the public. It also has an ambitious plan to vaccinate 50 million people in high-priority groups before the Lunar New Year travel peak in mid-February.

However, the efficacy rates of these vaccines – whose trials compare symptomatic infections in different groups – cannot show how effectively the vaccines stop transmission. There remains scant information about how well the vaccines stop asymptomatic infections. And not all vaccine trials show how well they can protect elderly or seriously ill patients.

Scientists, therefore, will closely monitor whether transmission rates drop in the new year, a factor closely linked to accessibility of the vaccines and the public’s willingness to take the jabs.

“[Experts will be looking for] decreasing hospitalisations, but also decreasing infections indicating decreased spread of the virus,” Plotkin said.

Michael Kinch, director of the Centre for Research Innovation in Biotechnology at Washington University in St Louis, said the duration of protection and virus mutation would determine if the vaccines could really end the pandemic.

“Evidence is mounting that natural infection – becoming sick from the virus – may not provide durable immunity in some. The key is whether a vaccine might overcome this limitation,” he said.

So far, the new variant discovered in London, although rendering the virus more transmissible, does not affect the spike protein targeted by the vaccines, but mutations that could potentially appear in the coming year will affect the success of inoculation programmes.

Safety issues – ranging from long-term and rare side effects, production quality and human errors in inoculation – can also pose challenges. Public confidence in the vaccines will be crucial to whether they will truly make a difference.

Singaporeans won’t be able to choose between Covid-19 vaccines

4 Jan 2021

For example, while many hailed the high efficacy of mRNA vaccines, George Gao Fu, head of the Chinese Centre for Disease Control and Prevention (CDC), has 

cautioned about unknown side effects

 because mRNA vaccines have never been used on healthy humans.

In addition to issues around supply shortage and access by developing countries to the vaccines, a concern raised by many organisations since early last year, large-scale and rapid inoculation can be messy.

Even a developed country such as Germany faces many bumps early in the roll-out, particularly because it is using 

Pfizer-BioNTech

 vaccines that require deep freezing. Eight workers at a care home were mistakenly given Pfizer-BioNTech doses five times the recommended dose. And 1,000 doses of the same vaccine were returned after being transported in a picnic hamper cool box instead of at the required minus 70 degrees Celsius (-94°F).

Chinese CDC chief George Gao Fu has cautioned about the unknown side effects of mRNA vaccines. Photo: AFP

Johnson & Johnson – which has taken up a significant percentage of the portfolio of the 

Covax Facility

, an international vaccine distribution mechanism led by the WHO – is likely to be next to finish its efficacy analysis.

Scientists are also pinning their hopes on protein subunit vaccines, a technology being used by US company Novavax and also by a team led by China CDC head Gao and Anhui Zhifei Longcom Biopharmaceutical. The technology is well proven and has been used in flu shots and hepatitis vaccines but such vaccines are difficult to design.

A candidate of a protein vaccine developed by pharmaceutical giant Sanofi and GSK must be delayed until late this year because of weak clinical data.

https://www.scmp.com/news/china/science/article/3116547/coronavirus-how-will-vaccine-advances-2020-alter-pandemic-path