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    Home > Active Ingredient News > Infection > Lancet: Nasal mucosal immunity is a key factor in the protection of the new crown

    Lancet: Nasal mucosal immunity is a key factor in the protection of the new crown

    • Last Update: 2023-02-01
    • Source: Internet
    • Author: User
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    As the main variant of the novel coronavirus (SARS-CoV-2), Omicron can significantly reduce the neutralization efficacy of different epitope neutralizing antibodies, and has strong immune escape characteristics, so there is still the possibility
    of breakthrough infection after "Yangkang".
    How long the antibodies produced after infection can be effective, and whether there are other ways to effectively reduce the risk of secondary infection, need to be thoroughly studied
    .


    A study 1 found published in LANCET INFECT DIS titled "Transmission of COVID-19 in 282 clusters in Catalonia, Spain: a cohort study.
    "
    : Increased viral load values in nasopharyngeal swabs in COVID-19 patients were associated with a greater risk of transmission of positive SARS-CoV-2 PCR tests between contacts, and higher viral load in swabs of asymptomatic contacts was associated with a higher risk of developing symptomatic COVID-19, suggesting that viral load may be the main driver of transmission; Moreover, the incubation period of asymptomatic contacts is shorter than that of contacts with low viral load, indicating that nasal viral load is high, the risk of SARS-CoV-2 transmission is high (Figure 1), and the incubation period is shorter, indicating that the level of nasal viral load is closely related to the severity of COVID-19 symptoms and transmissibility, further suggesting that reducing nasal viral load has an important role
    in the prevention and treatment of new coronavirus.


    Figure 1 PROBABILITY OF SYMPTOMATIC ILLNESS CAUSED BY VIRAL LOAD (SOURCE: LANCET INFECT DIS)


    The nasopharynx is the first site where the new coronavirus invades the human body, and the nasal antibody IgA produced by mucosal immunity is the most abundant mucosal antibody, which plays an important role
    in effectively neutralizing the upper respiratory tract virus.
    To reduce the risk of transmission, reduce SARS-CoV-2 infection, and reduce nasal viral load, this can be achieved by increasing nasal IgA antibodies
    .
    However, there are few studies on the long-term persistence of nasal antibodies, and the results are mixed, showing that nasal antibodies may persist for 3 to 9 months, and passive penetration of plasma antibodies into the mucosa may not provide persistent viral immunity
    .
    Therefore, understanding whether post-COVID-19 immunization can evoke a nasal IgA response is particularly important
    for developing vaccines to prevent infection and transmission and finding effective ways to enhance mucosal immunity.


    A study published in The Lancet eBioMedicine titled "SARS-CoV-2-specific nasal IgA wanes 9 months after hospitalisation with COVID-19 and is not induced by subsequent vaccination"2 Findings: After COVID-19 infection or vaccination, the body's blood and nasal passages produce high concentrations of antibodies that enhance the response to the original strain, Delta, and Omicron variants
    .
    However, for Omicron, the nasal IgA response is particularly short-lived
    .
    This may be an important reason why
    the new coronavirus can repeatedly infect the human body.



    In this follow-up study, the research team prospectively collected plasma and nasal samples
    from 446 adults hospitalized with COVID-19 between February 2020 and March 2021.
    The neutralization response
    of antibodies to the original strain, Delta, and Omicron (BA.
    1) variants was evaluated by measuring the antibodies in the participants' nose/plasma, as well as the duration of the antibodies.


    The results showed that nasal antibodies appeared within 4 weeks after infection with the original strain SARS-CoV-2, but returned to pre-infection levels after about 9 months and no longer functioned as a first-line defense; Antibodies in plasma appear within 14 days of infection, rise 2181-fold after 9 months, and remain above pre-infection levels thereafter for at least one year (Figure 2).

    And for Omicron, the nasal IgA response is particularly short-lived, only present 3-5 months after infection, indicating a higher risk of secondary infection with Omicron, and enhanced nasal mucosal immunity plays a key role in preventing secondary infection (Figure 3).


    Note: * = p < 0.
    05, ** = p < 0.
    01, *** = p < 0.
    001, **** = p < 0.
    0001.

    Figure 2 Nasal and plasma antibody reactions 12 months after new crown infection (Source: eBioMedicine)


    Note: * = p < 0.
    05, ** = p < 0.
    01, *** = p < 0.
    001, **** = p < 0.
    0001
    Figure 3 Nasal IgA and plasma IgG levels within one year after new crown infection (Source: eBioMedicine).

    The above two studies have shown that the strong immune evasion ability of the Omicron variant sharply increases the risk of reinfection and breakthrough infection (infection that occurs after full vaccination), and the plasma antibodies produced by immunization or infection with the new crown penetrate into the mucosa can not provide lasting viral immunity, but reduce nasal viral load, activate the nasal mucosa, enhance the self-cleaning ability and immunity of the nasal mucosa, effectively remove the virus, and reduce the risk of
    new coronavirus transmission.
    Therefore, strengthening nasal cleansing care and enhancing nasal mucosal immunity are particularly important
    for the prevention and treatment of the new coronavirus.
    Nasal cleaning can be carried out by rinsing, scrubbing and spraying to reduce nasal secretions, nasal inflammatory transmitters and the number of nasal microorganisms, increase mucosal cilia clearance, promote nasal mucosal recovery, maintain nasal physiological environment, reduce nasal inflammatory response and nosocomial infection incidence3

    .
    The Expert Consensus on the Prevention of Novel Coronavirus Infection by Nasal Saline Irrigation
    4 points out that nasal saline rinse, as a commonly used nasal local physical therapy, can reduce viral infection and accelerate inflammation recovery, and can be used as an effective means
    to prevent and treat novel coronavirus infection.
    Compared with traditional nasal irrigation, spray nasal cleaning is safer, more effective, more convenient, and has high compliance, and the irrigation solution enters the nasal cavity under controlled pressure without damaging the nasal mucosa, and the patient comfort is
    higher3
    .


    Nasal and mucosal immunity is a key factor in the protection against the new crown, and nasal washing is of great significance to remove the virus, which can reduce the risk of
    superinfection.



    References: 1.
    Marks M, Millat-Martinez P, Ouchi D, et al.
    Transmission of COVID-19 in 282 clusters in Catalonia, Spain: a cohort study.
    Lancet Infect Dis.
    2021 May; 21(5):629-636.
    doi: 10.
    1016/S1473-3099(20)30985-3.
    Epub 2021 Feb 2.
    Erratum in: Lancet Infect Dis.
    2021 Aug; 21(8):e208.
    2.
    Liew F, Talwar S, Cross A, et al.
    SARS-CoV-2-specific nasal IgA wanes 9 months after hospitalisation with COVID-19 and is not induced by subsequent vaccination.
    EBioMedicine.
    2022 Dec 16:104402.
    3.
    Xu Jiaojiao.
    Research progress on nasal cleaning in mechanically ventilated patients[J].
    Integrated Traditional Chinese and Western Medicine Nursing(Chinese and English),2019,5(06):213-215.
    )
    4.
    YU Shaoqing, YANG Yucheng, XU Yuanteng, et al.
    Expert consensus on nasal saline irrigation for the prevention of novel coronavirus infection[J].
    Chinese Journal of Ophthalmology, Otorhinolaryngology,2022,22(04):329-334+362



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