Why do COVID-19 boosters help protect me?


Plan A-Get the Jab!

COVID-19 is due to SARS-CoV-2 infecting you and to do this the virus has to invade your cells, notably those in the lung. Whilst T, B and the innate immune system protect you from the effects of infection, it is going to be antibody that protects you against infection. This is because the antibody binds to the virus and if it is against the Reecptor Binding Domain” it has the potential to stop the virus infecting cells.

SARS-CoV-2 spike protein antibody | Abcam

Vaccination creates T cells and B cells capable of attacking the virus. Whilst the B cells make antibody that can stop infection T cells are only activated after you have been infected. This is because T cells cannot see the virus. They can only see it when it is associated with your own cells. Therefore even in double vaxers as the antibodies wane after about 6 months it means that more people will get infected with time. This is more likely in people who make a low level antibody response in the first place, which is more common in people getting viral vectors verses the RNA vaccines (Pfizer, Moderna).

The way to get your antibody levels up is either via a third jab or by getting naturally infected. The problem with the latter approach is you dont know how infection is going to affect you. It would be as mild as a cold or sadly it can be much, much worse.

For people with MS, some MS-drugs limit the level of anti-SARS-COV-2 antibody level and this will affect your ability to block infection. This may affect your susceptibility to develop COVID-19. You are eligible for a booster if you are over 50 years old and if you are immunosuppressed then you could get a third jab and a booster. This gets your antibody level up and may protect you from infection.

Now remember to be watch-out for the onset of symptoms and remember it is easy to get a COVID-19 test if you live in the UK. I was tested alot last week because I had teaching and face to face duties. Its easy a small q-tip/cotton bud size swab in our throat and up your nose, 15-30minutes later you have a result.

However remember about a pulse oximeter, which measures your oxygen saturation levels. Those below 95-100% should have your alarm bells ringing as it may mean you need oxygen. So don’t wait and suffer call 111 and speak to a doctor.

Plan B?

If needed a pulse oximeter may help speed up access to an anti-viral. Because you have the data when you talk to the doctor.

In terms of anti-viral there are the new chemicals. These is remdesivir already and now molnupiravir has been approved in the UK and will be available soon. There are others in the pipeline such as a combination of PF-07321332 and ritonavir (Anti viral drug), which has posted good results. There are others too including anti-SARS-CoV-2 antibodies.

The anti-SARS-CoV-2 antibodies are often a cocktail of antibodies and historically were made to give to people who were infected, to act as an anti-viral. Sadly if you wait too long to start then it is often too late to get benefit.

Prof.Angry has always said the more useful approach would be use these as a prophylactic shield to prevent infection. It would have been so simple to give this to health care workers, or not as a control; and see how many were protected…but is wasn’t done, Now they are vaccinated. Sadly it is too late for some of the Health Care workers and an oppertunity was missed..

Of all the MS-drugs, the one that has recieved most adverse press has been ocrelizumab and rituximab as there are questions if people are more at risk of catching covid-19 and they clearly make a poor COVID-19 vaccine-related antibody response. The makers of this antibody also make an anti-SARS-CoV-2 cocktail and we have said it may be good to see these agents protect people who cannot make a antibody response. This antibody cocktail REGEN-COV®is made up of antibodies called casirivimab and imdevimab). This is approved as a 600mg dosing given up to 10 days after symptom onset. There is take about 27-32 days for half of the drugs to disappear.

However the idea of protective treatment was taken up by UK medical community and a number of trials were done using AZD7442. This is a combination of two long-acting antibodies that are engineered not to be destroyed. They have a half-life of around 90 days in humans. This was investigated in STORM-CHASER triAL was one. This failed to meet the endpoint of protection but a post trial analysis showed that if you got the protective antibody more than a week before you got infected, there was a massive reduction in prevention of symptomatic disease (ASTRAZENECA web site). However another trial was done and this was called PROVENT (Astrazeneca website) and this met its endpoint. The manufacturers have applied for emergency use approval.

However, there have been recent phase 3 trial reports of the effect of 1200mg casirivimab and imdevimab with high levels of protection over months and one wonders if a study to protect people on anti-CD20 will every be done.

However according to UK Government it is evident that:

The hosptialisation data strongly reinforces the need for all eligible age groups to get vaccinated and to take mitigating measures such as wearing a face covering in crowded places and ensuring good ventilation indoors.

This is particularly urgent for older people whose immunity may be waning given that several months have passed since they received their jabs.

The UK Government strongly encourage everyone who is eligible for a third dose or a booster shot to come forward without delay (Based on advice from UK Governments website)


For readers in the EU.

EMA’s human medicines committee (CHMP) has recommended authorising Ronapreve (casirivimab/imdevimab) and Regkirona (regdanvimab) for COVID-19.

The Committee recommended authorising Ronapreve for treating COVID-19 in adults and adolescents (from 12 years of age and weighing at least 40 kilograms) who do not require supplemental oxygen and who are at increased risk of their disease becoming severe. Ronapreve can also be used for preventing COVID-19 in people aged 12 years and older weighing at least 40 kilograms.

With regard to Regkirona regdanvimab, the Committee recommended authorising the medicine for treating adults with COVID-19 who do not require supplemental oxygen and who are also at increased risk of their disease becoming severe.

The CHMP will now send its recommendations for both medicines to the European Commission for rapid legally binding decisions.

COI: multiple none considered relevant

General Disclaimer: Please note that the opinions expressed here are those of the author and do not necessarily reflect the positions of the Barts and The London School of Medicine and Dentistry nor Barts Health NHS Trust and are not meant to be interpreted as personal clinical advice.  Please note that Professor Gavin Giovannoni has no responsibility for this blog.

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  • Great post and advice regarding covid as always. I will keep that to hand should it be needed
    Glad to see you are still here MD

  • Thanks. Any guidance for those of us on ocrelizumab who have had three vaccines – and just had a blood test showing we have not seroconverted – ie no antibodies? Just to continue being cautious?

    • I would say if you have not converted you are at risk from infection and likewise if you are a long time from your vaccine you are at risk of infection but I am sure those vaccines do protect you….I was convinced that someone I know….was going to have the roughest of rides when they got COVID…no vaccine response and as many risk factors as you can name….but they have pulled through, but we had the pulse oximeter that allowed us to get the attention of the health services to get them into hospital where they got some anti-virals and this is where the difference is. There are now options for people without antibody responses.

      We are currently formulating the options but someone infected who has been on ocrelizumab without an antibody response who has COVID requiring hospitalisation should be eligible for something. The issue is whether the centres are prescribing it and who is paying for it (internally). There is a protocol in place at Barts Health for antibody administration. We will soon know about the oral antiviral and here I suspect you will not need to be hospitalised but there is not much info on the MHRA site you take the drug twice a day for 5 days. We will give you an update

      • “I was convinced that someone I know….was going to have the roughest of rides when they got COVID…no vaccine response and as many risk factors as you can name….but they have pulled through”

        Glad the individual you knew with COVID made it out of the hospital MD1. Hope they do not experience any lasting issues.

        Now if we could only catch the allusive U.K. driver trying to knock off our precious bloggers. First Prof.G now Dr. Ide.…….What is going on over there? Be safe MD1/2 and NDG!!

        • Dr Ide was in the Netherlands so its an international conspiracy:-).

          Fear not MD2 does not use noise-cancelling ear phones whilst out walking, so I supect he can hear any quad bike out to get him…on the other hand NDG..the cat:-)… is climibing mountains and cliffs as a hobby so it is not a car that worries me. She has also had a near-death experience up a mountain and has definatly only has 8 lives left as she died for 45 minutes…Thats why she is wonder woman:-). That’s another story:-).

  • Regarding other viral infections what data do we have regarding MS patients on anti CD 20 drugs and and responses to influenza vaccines? Are MSers more likely to develop severe flu infections despite receiving the vaccine due to blunted ab?

    • Good question I dont know the answer but you are likely to make a blunted influenza responses, but this will have been the same issue for the past few years

  • Eligibility (or any other) difference between third jab and booster? Also, will booster become an annual event or will it be a six-month one? Perhaps no-one knows yet?

    • Booster…..and one over 50 and 6 months from jab….Third dose 8 weeks from the last dose, but for anti CD20 6 months and then booster in future.

      Will booster become annual event…I dont know but suspect if may be in the near future. As for 6 month verses annual, I guesss we need to see how long the booster lasts 6 months like two doses or longger after 3.

  • Why do you think Regen-cov lasted for 8 months given the 1 month half life? Is it the big dose or just coincidence given there were not that many infections even for placebo?

    • In the press release post it says 2-8 months but it is a big dose 1200mg remember 600mg of ocrelizumab lasts for 5-6 months

      • The 2-8 months bugged me too. I have a suspicion that the study is underpowered to say much of anything for the longer duration.

        Does ocrelizumab stay in the body in appreciable amounts for longer than a few months or does it simply take much longer for B cells to repopulate?

        • You are probably correct and until the study is published it is difficult to say. At the moment this antibody can be given monthly to people you will not mount a n antibody response it may be that this can be extended to 2-4 months by the double dosing.

          Ocrelizumab is still present as far as I know and once it disappears it comes back. Also remeber the studies were done in people that had B cells and maybe by cycle 2 or 3 there are few B cells to hoover the drug up and it may circulate for longer. It has a half life of about a month so simplistically month 1 =600mg month 2 =300mg month 3= 150mg, month 4=75mg, month 5 = 37.5mg month 6 = 18.75 month 7 = 600 + 9.375 we know that 20mg is depleting

  • Happy to see you posting again, MD. Has the research on covid-19 and anti-cd20s halted?
    Still wondering if anybody knows when there might be data on whether the T-cell vaccine responses make any real difference for the anti-cd20 treated PwMS (particularly in the ocrelizumab and rituximab-treated groups).

    • Has reasearch on anti CD20 and COVID halted….I doubt it we will get booster data next.

      We wrote to lab in Sweden this week they had not had enough cases…but they will keep us in the loop

  • Nice post
    Question : Do you advise 3 jab for old people and immunosuppressed or for every other person regardless off age

    • Personally I would offer a third dose to all because if you cut down the number of active infections…but at the moment the third dose is for anyone over 50 and/or immunosuppressed

      • Thanks
        I listen to some virologists saying that the 3 jab dont increase the breath of the antibody response nor the memory be cell pool

        Do you thing that we may have to do jab every year much like the flu shot?


        • The flu shot chnages because the virus changes each year, for COVID we have not yet had variant vaccines I know they are being developed.

  • I am having trouble reading today. Not because of my eyesight, but because of my broken heart. 2 nights ago, I watched the life drain from my Dad because of Covid. (through glass window while wearing an n95, completely covered up, still though, I was unable to hold his hand or talk to him) My Dad who never went anywhere. Who was double vaccinated (Moderna). Who was having some neurological setbacks & went to hospital by ambulance who then transferred him to a nursing/rehabilitation home for pt therapy & strengthening. Between the ambulance, hospital er, hospital admission or the nursing home, he contracted Covid. When I talked with him end of last week, I knew deep down that it would be last time. He was so weak & someone who could & would talk forever needed to hang up phone because it was too hard. We pushed for his transfer to hospital as nursing home had already delayed his treatment. After that call, my niece who works on a Covid floor elsewhere got involved & pushed for xray, decadron, etc . Within a half a week he went from 6 ltrs of O² to 60 ltrs if O² to being placed on a ventilator. Xray of lungs showed double pneumonia. Covid had eaten through his lungs as fast as Pacman in that video game. So please!, listen, read and pay attention to these articles from MouseDr & the others here. My heart is broken. My Dad who watched me come into this life on my birthday. My Dad who I watched leave this life on my birthday. 💔 😭

  • Hello, I am confused now. I thought the 3rd jab was for everyone in priority groups 1-9, with the booster for the severely immuncomprised which is In addition to the 3rd jab. So, if I’ve understood you correctly someone with ms, who is 49 and under, on DMT (such as CRAB or techfida) won’t get a 3rd jab or booster but someone who has no underlying issues but is 50 plus gets the 3rd jab?

  • MD, i am still not clear on what benefits having covid actually has to the anti CD20 population. Assuming we cant make antibodies are we just as at risk 3/4 weeks after the infection as we were before? yes, our tcells will be battle harderned but is that all?

    • Having COVID….down side = hospitalization and potentially dying this occurs after infection in the general population the problems really start about 7-10 days after infection when the virus starts to win. Death risk increases with disability, age, sex, co-morbidities etc. + Survival with Long covid

      Having COVID and surviving. Better all round immunity potentially with immune response to nucleocapsid as well as Spike and other viral proteins, it also means you may make a better response to vaccine. In many studies infection + one dose of vaccine = 2 doses of vaccine

      Having MS and DMT vaccine = benefits of reduced chance of hosptialization and dying

      Having MS + anti-CD20 and DMT vaccine….many people have not made a good antibody response after 2 doses especially. People with AZ vaccine without anti-CD20 will make a lower response. The third dose will make more people on anti-CD20 make an antibody response, the greater chance the longer interval from infusion. In the people who had a response this will be boosted. It will also increase the chance of a good T cell response

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