def get_email_content_45(df):
    """
    Return html string for 45 plus vaccine availability.

    Parameters
    ----------
    df : pandas.core.frame.DataFrame
        Pandas Dataframe containing data received from the API.

    Returns
    -------
    html_string_45 : str
        Html string for 45 plus vaccine availability.

    """
    html_string_45 = ""

    if df.empty:
        return html_string_45

    df_available_45 = df[(df["available_capacity"] > 0) & (df["min_age_limit"] == 45)]

    if not df_available_45.empty:

        html_string_45 += """<p align="center"><b><i> 45+ age group</i></b></p>
                        <br>
                        <br>"""

        for index, row in df_available_45.iterrows():
            html_string_45 += f"""
                <p>{row['available_capacity']} {row['vaccine']} are available at {row['name']}
                in {row['district_name']} for {row['min_age_limit']} and above years old.
                </p>
                <br>
                <br>"""

    return html_string_45