Someone asked about the course of COVID-19 and why you are OK and then not and so and I wish them a speedy recovery.
When you get infected it takes a few days for symptom onset, generally about 5 days and with omicron it may be a few days quicker. When symptoms appear your clock is ticking. You have five days to be offered anti-virals if you fit the bill in terms of risk. So make sure you can spot the symptoms, cough, temperature, loss of smell and others and have a lateral flow handy so you can pick the infection up. Remember you have to be tested positive, currently by polymerase chain reaction, so that could take a day to request it and it has to be sent to and fro so remember it is tick tick tick.
During the first few days your immune response is tackling the virus as it infects more of your lung tissue. It is a battle between your immune system and the virus. It takes about 7 days for you to deal with it if you are going to win and maybe abit quicker if you are vaccinated and even quicker with anti-virals.
But if the virus wins it blocks the anti-viral immune response and you may start to lose lymphocytes by about day 10, your symptoms may get worse and you get into breathing difficulties, you are clotting and at this point the anti-virals are not really effective. Hopefully you will pull through.
For some treatments you need to hosptialized and the quickest way there is if your oxygen levels drop
How Omicron gives the general public a taste of what its like to be CD20-depleted
Divergent SARS CoV-2 Omicron-specific T- and B-cell responses in COVID-19 vaccine recipients GeurtsvanKessel, C. H., Geers, D et al, Medrxiv BioRXiv 10.1101/2021.12.27.21268416
The severe acute respiratory distress syndrome coronavirus-2 (SARS-CoV-2) Omicron variant (B.1.1.529) is spreading rapidly, even in vaccinated individuals, raising concerns about immune escape. Here, we studied neutralizing antibodies and T-cell responses to SARS-CoV-2 D614G (wildtype, WT), and the B.1.351 (Beta), B.1.617.2 (Delta), and B.1.1.529 (Omicron) variants of concern (VOC) in a cohort of 60 health care workers (HCW) after immunization with ChAdOx-1 S, Ad26.COV2.S, mRNA-1273 or BNT162b2. High binding antibody levels against WT SARS-CoV-2 spike (S) were detected 28 days after vaccination with both mRNA vaccines (mRNA-1273 or BNT162b2), which significantly decreased after 6 months. In contrast, antibody levels were lower after Ad26.COV2.S vaccination but did not wane. Neutralization assays with authentic virus showed consistent cross-neutralization of the Beta and Delta variants in study participants, but Omicron-specific responses were significantly lower or absent (up to a 34-fold decrease compared to D614G). Notably, BNT162b2 booster vaccination after either two mRNA-1273 immunizations or Ad26.COV.2 priming partially restored neutralization of the Omicron variant, but responses were still up to-17-fold decreased compared to D614G. CD4+ T-cell responses were detected up to 6 months after all vaccination regimens; S-specific T-cell responses were highest after mRNA-1273 vaccination. No significant differences were detected between D614G- and variant-specific T-cell responses, including Omicron, indicating minimal escape at the T-cell level. This study shows that vaccinated individuals retain T-cell immunity to the SARS-CoV-2 Omicron variant, potentially balancing the lack of neutralizing antibodies in preventing or limiting severe COVID-19. Booster vaccinations may be needed to further restore Omicron cross-neutralization by antibodies.
So we know that the number of severe cases are low whilst omicron cases are going through the roof. We also know that people who have been vaccinated are susceptible to omicron infection and that boosters reduce reduce the risk if infection. So do T cells do the business?
De Marco et al. Preserved T cell reactivity to the SARS-CoV-2 Omicron variant indicates continued protection in vaccinated individuals. BioRXiv doi: https://doi.org/10.1101/2021.12.30.474453
T cell responses to peptides covering the mutated regions in the Omicron variant were decreased by over 47% compared to the same regions of the ancestral vaccine strain. However, overall reactivity to the peptide library of the full-length protein was largely maintained (estimated 83%). No significant differences in loss of immune recognition were identified between groups of donors with different vaccination and/or infection histories. Conclusions and Relevance: We conclude that despite the mutations in the Spike protein, the SARS-CoV-2 Omicron variant is nonetheless recognized by the cellular component of the immune system. It is reasonable to assume that protection from hospitalization and severe disease is maintained.